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#452 From: "Nicolae Sfetcu" <amacom@...>
Date: Mon Jul 1, 2002 6:48 pm
Subject: Low Voltage Alarm nsfetcu
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Low Voltage Alarm

This low voltage circuit can be used to monitor batteries and other volatile sources of current for problems. The circuit sounds an alarm and lights an LED, but can be interfaced to any number of other circuits for many different uses.

Schematic

Parts:

Part	Total Qty.	Description	Substitutions
R1, R3	2	1K 1/4W Resistor
R2	1	5K Pot
U1	1	LM339 Op Amp IC
D1	1	1N5233B Zener Diode
D2	1	LED
BZ1	1	Piezo Buzzer
MISC	1	Board, wire, socket for IC

Notes:

1. The circuit will operate from 9V to 12V.

2. Adjust R2 until the alarm goes off at the correct voltage.

http://www.aaroncake.net/circuits/index.asp

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#453 From: "Nicolae Sfetcu" <amacom@...>
Date: Tue Jul 2, 2002 4:03 pm
Subject: Led Pilot Light nsfetcu
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Led Pilot Light

LED's are funny things. They only work at Vdc within specific tolerances, and normally connected with a current limiting resistor to the powersource. Instead of a resistor, you can use a FET (Field Effect Transistor) such as the ECG312, NTE312, or others.
When the gate and the source are connected together, it behaves as a current regulator. In the circuit above the current is constant between 6 and 8 mA at 5 to 30Vdc.
If a diode is added (the 1N4148 is optional) this circuit is protected agains polarity reversal and can be connected to a AC source of 5 to 20 Vac.

http://www.uoguelph.ca/~antoon/circ/circuits.htm

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#454 From: "Nicolae Sfetcu" <amacom@...>
Date: Wed Jul 3, 2002 2:37 pm
Subject: MC14093 (CMOS) Quad 2-Input NAND Schmitt Trigger nsfetcu
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MC14093 (CMOS) Quad 2-Input NAND Schmitt Trigger Data sheet Direct substitute for CD4093, MC14011B

The MC14093B Schmitt Trigger is constructed with MOS P-channel and N-channel enhancement mode devices in a single monolithic structure. These devices find primary use where low power dissipation and/or high noise immunity is desired. The MC14093B may be used in place of the MC14011B quad 2-input NAND gate for enhanced noise immunity or to "square-up" slowly changing waveforms.

Equivalent schematic

Features:

Supply voltage range is 3.0Vdc to 18Vdc.

Capable of driving two low-power TTL loads or one low-power Schottky TTL load over the rated temperature range.

Double diode protection on ALL inputs.

Pin-for-pin compatible with the CD4093.

Can be used to replace the MC14011B.

Absolute Maximum Ratings:

Supply voltage for MC14093B is -0.5 to +18 volt dc. Logic diagram

Input or Output voltage (DC or Transient) -0.5 to Vdd +0.5volt dc.

Input or Output current (DC or Transient), per pin is approx. 10mA.

Power dissipation 500 milliWatts.

Storage temperature range from -65 to +150 �C.

Lead temperature (soldering, up to 8 sec) 260 �C.

Suffix's:

The 'L' suffix stands for Ceramic package (mostly used in the Industry), case 632.

The 'P' suffix stands for Plastic package, case 646.

Notes:
- Tie unused inputs always to an appropriate voltage level like +Vcc or Ground. Unused outputs must remain open.
- The MC14093B contains protection circuitry to guard against damdage due to high static voltages or electric field. However, precautions must be take to avoid applications of any voltage higher than maximum rated voltage to this high impedance circuit. For proper operation, Vin and Vout should be constrained to the range Vss smaller-than Vdd.

http://www.uoguelph.ca/~antoon/gadgets/gadgets.htm

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#455 From: "Nicolae Sfetcu" <amacom@...>
Date: Thu Jul 4, 2002 5:14 pm
Subject: MC1455 (CMOS)Timer/Oscillator nsfetcu
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MC1455 (CMOS)Timer/Oscillator Data sheet Direct substitute for LM555, NE555

The MC1455 silicon monolithic timing circuit is a highly stable controller capable of producing accurate time delays, or oscillation. In the time delay mode of operation, the time is precisely controlled by one external resistor and capacitor. For a stable operation as an oscillator, the free running frequency and the duty cycle are both accurately controlled with two external resistors and one capacitor. The circuit may be triggered and reset on falling waveforms, and the output structure can source or sink up to 200 mA or drive MTTL circuits.

22-Second solid-state time delay relay circuit
Click here to enlarge

Features:

Turn off time less than 2 micro seconds.

Maximum operating frequency greater than 500KHz.

Timing from microseconds to hours.

Operates in both astable and monostable modes.

High output current.

Adjustable duty-cycle.

TTL compatible.

Temperature stability of 0.005% per �C.

Rise and Fall times of output is 100nS typical.

Normally "on" or normally "off".

Output can also drive MTTL circuits.

Direct pin-compatible with the LM555 & NE555 timers.

Some Applications:

Block Diagram

Precision Timing.

Pulse generation.

Sequential timing.

Timedelay generation.

Pulse width modulation.

Pulse position modulation.

Missing Pulse Detector.

Absolute Maximum Ratings:

Supply voltage for MC1455 is +18 volt.

Discharge current (pin 7) is 200mA.

Power dissipation 680 milliWatts.

Operating temperature range for MC1455G, MC1455P1, NE555V, MC1455D,
and MC1455U are 0�C to +70�C. For MC1455BP1 is that -40�C to +85�C

Storage temperature range from -65 to -150 �C.

Lead temperature (soldering, up to 60 sec) 300 �C.

Suffix's:

The 'G' suffix (e.i. MC1455G) stands for Metal package (can), case 601-04.

The 'P1' suffix stands for Plastic package (the most common), case 626-05.

The 'U' suffix stands for Ceramic package (mostly used in the Industry), case 693-02.

The 'L' suffix stands for Ceramic package (mostly used in the Industry), case 632-08.

The 'D' suffix stands for Surface Mount, Plastic package, case 751-02 or SO-8.

The 'D, N, or FE' suffix can be found for the 8-pin dip packages.

The 'F' suffix is the 14 pin version of the 8-pin dip. Pins 2,5,7,9,11, and 13 are not connected.

Notes:

Supply current when output high typically 1mA or less.

Tested at Vcc=5V and Vcc=15V.

This will determine the maximum value of Ra+Rb, for 15V operation, the max total
R = 10 megohm, and for 5V operation, the max total of R = 3.4 megohm.

Specified with trigger input high.

Time measured from a positive going input pulse from 0 to 0.8 x Vcc into the threshold
to the drop from high to low of the output. Trigger is tied to treshold.

http://www.uoguelph.ca/~antoon/gadgets/gadgets.htm

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#456 From: "Nicolae Sfetcu" <amacom@...>
Date: Mon Jul 8, 2002 8:25 pm
Subject: Simple microphone preamplifier nsfetcu
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Simple microphone preamplifier

Original Document at: http://www.hut.fi/~then/circuits/micamp.html

This is a simple microphone preamplifer circuit which you can use between your microphone and stereo amplifier. This circuit amplifier microphone suitable for use with normal home stereo amplifier line/CD/aux/tape inputs. This mic preamp can take both dynamic and electret microphone inputs (preamplifer provides power foe electret microphone elements). The idea of this circuit is to keep the design as simple as possible to be easy to build. That was my goal when I needed a simple external microphone preamplifer for my mixer. The performance of the circuit is nothing superior but can be used with many not so serious projects.

The circuit is a simple one transistor amplifier with amplification of about 30-40 dB (depends on transitor, temperature and voltage). The dynamic mic input is just a simple one transistor amplifier circuit with nothing special. Electret microphone input has a resistor R1 fo feeding current through electret microphone capsule when it is connected to the electret microphone input. Electret microphone needs some current (about 1 mA) flowing through it to operate, because there is a small amplifier circuit inside the microphone capsule. This circuit is suitable for all typical cheap electret campsules which available from any electronic component shop. Because electret microphones have higher signal level output, it is quite easy to overdrive the amplifier when you shout to electret microphone.

The circuit is bet to build to a small metal box where you have a small 9V battery for powering it. Battery power and metal box keep noise away.

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#457 From: "Nicolae Sfetcu" <amacom@...>
Date: Tue Jul 9, 2002 2:25 pm
Subject: Video Conectors nsfetcu
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9 PIN D-SUB FEMALE (At the videocard)
9 PIN D-SUB MALE (At the monitor cable)

Texts describing the connectors

Below the pictures there is texts that describes the connectors. Including the name of the physical connector.

5 PIN DIN 180� (DIN41524) at the computer.

Pin table

The pin table is perhaps the information you are looking for. Should be simple to read. Contains mostly the following three columns; Pin, Name & Description.

Pin	Name	Description
1	CLOCK	Key Clock
2	GND	GND
3	DATA	Key Data
4	VCC	+5 VDC
5	n/c	Not connected

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#458 From: "vincent_bw" <vincent_bw@...>
Date: Tue Jul 9, 2002 9:01 am
Subject: scheme ionezer or air purifier vincent_bw
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Hello,

I need scheme ionezer or air purifier. Can anybody help me?
Thank You. God Bless You, Vincent.

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#459 From: "thekoookooo" <thekoookooo@...>
Date: Thu Jul 11, 2002 3:02 am
Subject: ADC0808 problems. thekoookooo
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Hello everybody, here is my problem:

I'm using an analog to digital converter (the ADC0808) in order to
get position information from several potentiometers fixed on
different shafts(it's for a robot arm).
I build the circuit and i'm using a program in C (made by me) in
order to see the data on the screen. The chip is supposed to convert
a value 0-5Vdc into a number 0-255. It does it but it acts pretty
strange. Example: it's linear from 0 to 32 but once there it jumps to
64, goes linear again until 99 then gets back to 33 and continues
linearly. Everything else in the circuit works fine, i'm sure the
problem is my ADC.
What do you think about that?
Thanks a lot.

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#460 From: Paul Perry <pfperry@...>
Date: Thu Jul 11, 2002 8:16 am
Subject: Re: [Electronica] ADC0808 problems. pfperry@...
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At 03:02 AM 11/07/02 -0000, you wrote:
>
>linearly. Everything else in the circuit works fine, i'm sure the
>problem is my ADC.
>What do you think about that?

I think maybe one output pin  of your dac is shorted out.
Also, when you say 'everything else is fine', I hope you have actually
measured the input to the ADC as the pot turns ;D

paul perry Melb AUstralia

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#461 From: "Nicolae Sfetcu" <amacom@...>
Date: Mon Jul 15, 2002 8:57 pm
Subject: FET Audio Mixer nsfetcu
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FET Audio Mixer

This simple circuit mixes two or more channels into one channel (eg. stereo into mono). The circuit can mix as many or as few channels as you like and consumes very little power. The mixer is shown with two inputs, but you can add as many as you want by just duplicating the "sections" which are clearly visible on the schematic.

Schematic

Parts

Part	Total Qty.	Description	Substitutions
R1, R3	2	10K Pot
R2, R4	2	100K 1/4 W Resistor
R5	1	6.8K 1/4 W Resistor
C1, C2, C3	3	0.1uF Capacitor
Q1	1	2N3819 Junction FET
MISC	1	Wire, Shielded (Metal) Case, Phono Or Other Plug For Output

Notes

1. As many or as few channels as are required can be added to the mixer. Do this by just duplicating the input "sections" which are clearly shown on the schematic. One version of this mixer I saw had 25 inputs!

2. A shielded case is probably needed to reduce hum and help stop oscillations.

3. The circuit can be powered by a single 9 volt battery.

http://www.aaroncake.net/circuits/index.asp

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#462 From: "andrewyslee" <andrewlee@...>
Date: Tue Jul 16, 2002 8:05 am
Subject: modem lights andrewyslee
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Hi,

Anybody knows where to get a circuit that will enable an LED to light
up and/or blink when a pin on the serial/parallel port is
recieving/sending signal just like those blinking lights in a modem?

Thanks in advance.

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#463 From: "Nicolae Sfetcu" <amacom@...>
Date: Tue Jul 16, 2002 4:37 pm
Subject: Microphone Mixer nsfetcu
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Microphone Mixer

By Anatoly I. Shikhatov: This relatively simple mixer was designed for three dynamic microphones, but can be re-designed for more or less. Level and tone controls are available to tailor the sound to your needs.

Schematic

Parts:

Part	Total Qty.	Description	Substitutions
R1, R2, R3	3	1K 1/4W Resistor
R4, R5, R6	3	10K Logarithmic Pot
R7	1	1Meg 1/4W Resistor
R8, R10	2	10K 1/4W Resistor
R9, R11	2	100K Linear Pot
C1, C2, C5, C6	4	0.1uF Ceramic Disc Capacitor
C3, C4	2	22nF Ceramic Disc Capacitor
U1, U2	2	741 Op Amp
J1, J2, J3	3	Input Jacks Of Your Choice
MISC	1	Board, Wire, Knobs, IC Sockets

Notes:

1. Email Anatoly I. Shikhatov with questions, comments, etc.

2. R1-R3 are level controls. R9 and R11 control bass and treble, respectively.

3. Since the circuit draws such low current, two 9V batteries can be used for a power supply.

4. Building the mixer in a metal case will cut down on noise.

http://www.aaroncake.net/circuits/index.asp

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#464 From: "Nicolae Sfetcu" <amacom@...>
Date: Wed Jul 17, 2002 5:27 pm
Subject: NE555 Timer/Oscillator Data sheet nsfetcu
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NE555 Timer/Oscillator Data sheet Similar to: LM555-SE555C-MC1455P1-NTE955M-ECG955M

The NE555 silicon monolithic timing circuit is a highly stable controller capable of producing accurate time delays, or oscillation. In the time delay mode of operation, the time is precisely controlled by one external resistor and capacitor. For a stable operation as an oscillator, the free running frequency and the duty cycle are both accurately controlled with two external resistors and one capacitor. The circuit may be triggered and reset on falling waveforms, and the output structure can source or sink up to 200 mA.

Features: block diagram

Turn off time less than 2 micro seconds.

Maximum operating frequency greater than 500KHz.

Timing from microseconds to hours.

Operates in both astable and monostable modes.

High output current.

Adjustable duty-cycle.

TTL compatible.

Temperature stability of 0.005% per �C.

Rise and Fall times of output is 100nS typical.

The MC1455 (cmos) has a normally "on" or normally "off".

The MC1455 (cmos) output can also drive MTTL circuits.

The MC1455 (cmos) is direct pin-compatible with the NE555 timers.

Some Applications:

Precision Timing.

Pulse generation.

Sequential timing.

Timedelay generation.

Pulse width modulation.

Pulse position modulation.

Missing Pulse Detector (used in Crashed Aircraft Locator article).

Absolute Maximum Ratings:

Supply voltage for SE555 +18 volt. For NE555 & SE555C +16 volt.

Discharge current (pin 7) is 200mA.

Power dissipation 600 milliWatts. For the MC1455 is that 680mW.

Operating temperature range for NE555 0 to 70�C, for SE555 & SE555C -55 to 125�C.

Storage temperature range from -65 to 150�C.

Lead temperature (soldering, up to 60 sec) 300�C.

Suffix's: pins

The 'G' suffix (e.i. xx555G) stands for Metal package (can), case 601-04.

The 'P1' suffix stands for Plastic package (the most common), case 626-05.

The 'U' suffix stands for Ceramic package (mostly used in the Industry), case 693-02.

The 'L' suffix stands for Ceramic package (mostly used in the Industry), case 632-08.

The 'D' suffix stands for Surface Mount, Plastic package, case 751-02 or SO-8.

The 'D, N, or FE' suffix can be found for the 8-pin dip packages.

The 'F' suffix is the 14 pin version of the 8-pin dip. Pins 2,5,7,9,11, and 13 are not connected.

Notes:

Supply current when output high typically 1mA or less.

Tested at Vcc=5V and Vcc=15V.

This will determine the maximum value of Ra+Rb, for 15V operation, the max total
R = 10 megohm, and for 5V operation, the max total of R = 3.4 megohm.

Specified with trigger input high.

Time measured from a positive going input pulse from 0 to 0.8 x Vcc into the threshold
to the drop from high to low of the output. Trigger is tied to treshold.

555 Equivalent Schematic

http://www.uoguelph.ca/~antoon/gadgets/gadgets.htm

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#465 From: "Nicolae Sfetcu" <amacom@...>
Date: Thu Jul 18, 2002 3:11 pm
Subject: NE556 Dual Timer/Oscillator nsfetcu
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NE556 Dual Timer/Oscillator Data sheet Similar to: LM556-SE556C-MC3453-MC3556-NTE978-ECG978

The 556 Dual Monolithic timing circuit is a highly stable controller capable of producing accurate time delays, or oscillation. The 556 is simply a dual 555. Timing is provided by an external resistor and capacitor for each timing function. The two timers operate independently of each other sharing only Vcc and Ground. The circuit may be triggered and reset on falling waveforms, and the output structure may source or sink up to 200 mA.

Features:

The NE556/SE556 timers can be directly replaced by the CMOS td3

types MC3456/MC3556.

Timing from microseconds to hours.

Supply voltage from +4.5V (min) to +18V (max).

Replaces two 555 timers.

Maximum operating frequency greater than 500Khz.

Operates in both astable and monostable modes.

High output current.

Adjustable duty-cycle.

TTL compatible.

Temperature stability of 0.005% per �C.

Rise and Fall times of output is 100nS typical.

SE556 type MIL STD 883A, B, C is available.

Some Applications:

Precision Timing.

Pulse shaping. td2

Pulse generation.

Sequential timing.

Timedelay generation.

Pulse width modulation.

Pulse position modulation.

Missing Pulse Detector.

Tone burst generator.

Appliance timing.

Traffic light control.

Touch tone decoder.

Absolute Maximum Ratings:

Supply voltage for SE556 +18 volt. For NE556 & SE556C +16 volt.

Discharge current (pin 7) is 200mA.

Power dissipation 600 milliWatts.

Operating temperature range for NE556 0 to 70 �C, for SE556 & SE556C -55 to -125 �C.

Storage temperature range from -65 to -150 �C. td1

Lead temperature (soldering, up to 60 sec) +300 �C.

Notes:

Supply current when output high typically 1mA or less.

Tested at Vcc=5V and Vcc=15V.

This will determine the maximum value of Ra+Rb, for 15V operation, the max total
R = 10 megohm, and for 5V operation, the max total of R = 3.4 megohm.

Specified with trigger input high.

Time measured from a positive going input pulse from 0 to 0.8 x Vcc into the threshold
to the drop from high to low of the output. Trigger is tied to treshold.

Available in D, F, N, plastic packages. 'D' suffix being the SO-8 surface mount type.

http://www.uoguelph.ca/~antoon/gadgets/gadgets.htm

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#466 From: "Nicolae Sfetcu" <amacom@...>
Date: Mon Jul 22, 2002 4:45 pm
Subject: Testing a MosFet nsfetcu
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Testing a MosFet

This testing procedure is for use with a digital multimeter in the diode test-range with a minimum of 3.3 volt over d.u.t. (diode-under-test)

testing a mosfet

Connect the 'Source' of the MosFet to the meter's negative (-) lead.

1) Hold the MosFet by the case or the tab but don't touch the metal parts of the test probes with any of the other MosFet's terminals until needed.

2) First, touch the meter positive lead onto the MosFet's 'Gate'.

3) Now move the positve probe to the 'Drain'. You should get a 'low' reading. The MosFet's internal capacitance on the gate has now been charged up by the meter and the device is 'turned-on'.

4) With the meter positive still connected to the drain, touch a finger between source and gate (and drain if you like, it does not matter at this stage). The gate will be discharged through your finger and the meter reding should go high, indicating a non-conductive device.

Such a simple test is not 100% -- but is useful and usually adequate.

When MOSFETS fail they often go short-circuit drain-to-gate. This can put the drain voltage back onto the gate where ofcourse it feeds (via the gate resistors) into the drive circuitry, prossibly blowing that section. It will also get to any other paralleled MosFet gates, blowing them also.
So, if the MosFets are deceased, check the drivers as well! This fact is probably the best reason for adding a source-gate zener diode; zeners fail short circuit and a properly connected zener can limit the damage in a failure! You can also add subminiature gate resistors -- which tend to fail open-circuit (like a fuse) under this overload, disconnecting the dud MosFet's gate.
http://www.uoguelph.ca/~antoon/gadgets/circuits.htm

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#467 From: "Nicolae Sfetcu" <amacom@...>
Date: Tue Jul 23, 2002 5:49 pm
Subject: Null Modem nsfetcu
Send Email

Nullmodem Cable, 9 to 9 Pin Female D-SUB

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#468 From: "Nicolae Sfetcu" <amacom@...>
Date: Tue Jul 23, 2002 5:55 pm
Subject: Phone Busy Indicator nsfetcu
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Phone Busy Indicator

Have you ever been using the modem or fax and someone else picks up the phone, breaking the connection? Well, this simple circuit should put an end to that. It signals that the phone is in use by lighting a red LED. When the phone is not in use, a green LED is lit. It needs no external power and can be connected anywhere on the phone line, even mounted inside the phone. Note: This circuit may cause problems for some when used. You may want to build a different circuit.

Schematic

Parts:

Part	Total Qty.	Description	Substitutions
R1	1	3.3K 1/4 W Resistor
R2	1	33K 1/4 W Resistor
R3	1	56K 1/4 W Resistor
R4	1	22K 1/4 W Resistor
R5	1	4.7K 1/4 W Resistor
Q1, Q2	2	2N3392 NPN Transistor
BR1	1	1.5 Amp 250 PIV Bridge Rectifier
LED1	1	Red LED
LED2	1	Green LED
MISC	1	Wire, Case, Phone Cord

Notes:

1. This is a very simple circuit and is easily made on a perf board and mounted inside the phone.

2. LED1 and LED2 flash on and off while the phone is ringing.

3. Do not worry about mixing up the Tip and Ring connections.

4. The ring voltage on a phone line is anywhere from 90 to 130 volts. Make sure no one calls while you are making the line connections or you'll know it. :-)

5. In some countries or states you will have to ask the phone company before you connect this to the line. It might even require an inspection.

6. If the circuit causes distortion on the phone line, connect a 680 ohm resistor in between one of the incoming line wires and the bridge rectifier.

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#469 From: "Nicolae Sfetcu" <amacom@...>
Date: Tue Jul 23, 2002 5:55 pm
Subject: Phone Busy Indicator nsfetcu
Send Email

Phone Busy Indicator

Schematic

Parts:

Part	Total Qty.	Description	Substitutions
R1	1	3.3K 1/4 W Resistor
R2	1	33K 1/4 W Resistor
R3	1	56K 1/4 W Resistor
R4	1	22K 1/4 W Resistor
R5	1	4.7K 1/4 W Resistor
Q1, Q2	2	2N3392 NPN Transistor
BR1	1	1.5 Amp 250 PIV Bridge Rectifier
LED1	1	Red LED
LED2	1	Green LED
MISC	1	Wire, Case, Phone Cord

Notes:

1. This is a very simple circuit and is easily made on a perf board and mounted inside the phone.

2. LED1 and LED2 flash on and off while the phone is ringing.

3. Do not worry about mixing up the Tip and Ring connections.

4. The ring voltage on a phone line is anywhere from 90 to 130 volts. Make sure no one calls while you are making the line connections or you'll know it. :-)

5. In some countries or states you will have to ask the phone company before you connect this to the line. It might even require an inspection.

6. If the circuit causes distortion on the phone line, connect a 680 ohm resistor in between one of the incoming line wires and the bridge rectifier.

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#470 From: "Nicolae Sfetcu" <amacom@...>
Date: Wed Jul 24, 2002 3:56 pm
Subject: Null Printer Adapter nsfetcu
Send Email

Null Printer Adapter

This circuit is a simple adapter for PC parallel port to think that there is a printer connected to computer. This adapter is useful for testing printing speed with different software and as a part of your own designs.

You can use this circuit to connect your simple circuits to the parallel port. Usually many home-made circuits use parallel port in a way which you have to use direct I/O commands to control the parallel port to be able to communicate to your circuit. Unfortunately this approach is not always possible, because some operating system prohibit the programs to directly control the computer hardware. In this situation you might want to use standard operating system printer printing functions for sending data to your circuit, but it does not work because your circuit does not generate the handshakes that are needed.

With this adapter you don't have to worry about generating handshaking signals in your own circuits. This simple circuit consists of only few wires connected to parallel port connector and it makes the computer to think that there is a real printer connected to parallel port and accepting the data.

Circuit operation

This circuit works using following principles: Bysy and paper out signals which normally come from printer have to be kept low, so they are tied to ground. Select and error signals which normally come from printer must be kept high, so they are connected to reset output in parallel port. Acknowledge signal is directly driven from strobe line.

Circuit diagram

Connecting diagram ASCII presentation:

1 -> 10
11 -> 12,18
13 -> 15,16

Circuit diagram picture:

The circuit is very easy to built inside the printer connector shell. The circuit can be easily shown in ASCII and graphical presentation. All pin numbers are for 25 pin D connector (as in PC parallel port).

Another proposed circuit

I saw the following schematics was shown on Dontronics web pages. The circuit is simpler because it does not connect to all handshaking pins. The basic idea is the same as in the circuit shown above.

Make up a DB-25 plug as follows:

Connect Strobe (1) to ACK (10)
Connect Busy (11) to PE (12). Connect these via a 270 Ohm resistor to Ground (18 to 25).
Connect SLCT (13) ro ERROR (15). Connect these via a 22K resistor to INIT (16).

http://www.hut.fi/~then/

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#471 From: "Nicolae Sfetcu" <amacom@...>
Date: Thu Jul 25, 2002 1:11 pm
Subject: Ringing Phone Light Flasher nsfetcu
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Ringing Phone Light Flasher

I have received several emails asking how to connect up some lights so that when the phone rings, they flash. This is very useful in a situation were there is lots of noise and it is impossable to hear the phone, such as a workshop. Here is such a device. The ring detect part of this circuit came from http://www.hut.fi/Misc/Electronics/circuits/telephone_ringer.html.

Schematic

Parts:

Part	Total Qty.	Description	Substitutions
C1	1	0.47uF 250V Capacitor
R1, R2	2	10K 1/4 W Resistor
R3	1	1K 1/4W Resistor
D1, D2	2	20V 1/4W Zener Diode
D3	1	1N4148 Diode
Q1	1	2N3904 NPN Transistor	2N2222
U1	1	4N27 Opto Isolator
RELAY	1	Solid State Or Regular Relay (See Notes)
MISC	1	Case, Wire, Board

Notes:

1. You may need to use a lower voltage zener for D1 and D2.

2. You can use a regular relay instead of a solid state relay, but the arcing accross the contacts may destroy it pretty quickly.

3. Be very sure that you have not accidentally connected 120V to the phone line when building and installing this circuit.

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#472 From: "Nicolae Sfetcu" <amacom@...>
Date: Fri Jul 26, 2002 7:59 pm
Subject: Cut Phone Line Detector nsfetcu
Send Email

Cut Phone Line Detector

When the circuit detects that a phone line has been cut, it activates a MOSFET which can be used to drive a relay, motor, etc. It can also be connected to a security system.

Schematic

Parts

Part	Total Qty.	Description	Substitutions
R1, R2, R3	3	22 Meg 1/4 W Resistor
R4	1	2.2 Meg 1/4 W Resistor
C1	1	0.47uF 250V Mylar Capicitor
Q1	1	2N3904 Transistor	2N2222
Q2	1	2N3906 Transistor
Q3	1	IRF510 Power MOSFET
D1	1	1N914 Diode
Load	1	See "Notes"
MISC	1	Wire, Phone Connectors, Circiut Board

Notes

1. The "Load" can be a relay, lamp, motor, etc. The circuit can also be connected to a security system to sound an alarm in case the phone line is cut.

2. If the circuit is connected to a security system or other circuit, both circuits must be electrically isolated from each other using an opto-isolator, relay, etc. This also means that the Cut Phone Line Detector must be powered by a seperate 9V supply.

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#473 From: Advantis <advantis@...>
Date: Sat Jul 27, 2002 10:09 pm
Subject: C9018 Transistor advantis_gmx...
Send Email

Hello

   Does anyone know some equivalence to the C9018 transistor? I wan
   unable to find any data on the Net about it.

--
Best regards,
  Advantis                          mailto:advantis@...

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#474 From: "Nicolae Sfetcu" <amacom@...>
Date: Mon Jul 29, 2002 2:04 pm
Subject: Logic probe with Pulse nsfetcu
Send Email

Parts List:
R1 = 1K C1,C2 = 0.01uF (10 nanoFarad)
R2 = 150 ohm T1 = 2N2219(A), NTE123, or TUN
R3 = 150 ohm D1 = 1N914
R4 = 3K3 IC1 = 7400, quad 2-input NAND gate
R5 = 20K IC2 = 555, timer/oscillator
R6 = 390 ohm Led 1,2,3 = Red,Green, Yellow. Ultra bright, 3mm
R7 = 150 ohm S1 = Switch, on-off

Description:
      One of the most frustrating problems with experimenting is not be able to check the logic state of TTL or CMOS ic's without the use of a triggered oscilloscope. The schematic diagram above shows a simple and inexpensive way of building a 'Logic Probe' yourself. It will provide you with three visible indicators; "Logic 1" (+, red led), "Logic 0" (-, green led), and "Pulse" (yellow led).

      The yellow or 'pulse' led comes on for approximately 200 mSec to indicate a pulse without regards to its width. This feature enables one to observe a short-duration pulse that would otherwise not be seen on the logic 1 and 0 led's. A small switch (subminiature slide or momentary push) across the 20K resistor can be used to keep this "pulse" led on permanently after a pulse occurs.
In operation, for a logic 0 input signal, both the '0' led and the pulse led will come 'ON', but the 'pulse' led will go off after 200 mSec. The logic levels are detected via resistor R1 (1K), then amplified by T1 (NPN, Si-AF Preamplifier/Driver), and selected by the 7400 IC for what they are. Diode D1 is a small signal diode to protect the 7400 and the leds from excessive inverse voltages during capacitor discharge.

      For a logic '1' input, only the logic '1' led (red) will be 'ON'. With the switch closed, the circuit will indicate whether a negative-going or positive-going pulse has occurred. If the pulse is positive-going, both the '0' and 'pulse' led's will be on. If the pulse is negative-going, the '1' and 'pulse' led's will be on.

http://www.uoguelph.ca/~antoon/circ/circuits.htm

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#475 From: "Nicolae Sfetcu" <amacom@...>
Date: Tue Jul 30, 2002 1:54 pm
Subject: Pre-amplifier nsfetcu
Send Email

Pre-amplifier

PARTS
C1: 100uF
C2: 33uF
C3: 33uF
C4: 0.1uF
C5: 100uF
R1: 10K variable resistor
R2: 1K
R3: 1M
R4: 1M
R5: 1K
R6: 10K
R7: 1K
T1: BC 548 or simillar
T2: BC 558 or similar
T3: BC 548 or simillar
T4: BC 558 or similar
IC1, IC2: 741 / 351 Operational Amplifier IC

EXPLANATION

This circuit is a one-channel pre-amplifier using two 741 or 351 operational amplifiers.
The part of the circuit in the yellow box provides and regulates zero volts or ground. R1 should be adjusted so that pin 3 of IC1 is half the supply voltage. The reason the output of the IC is buffered is because the IC has a regulated output of about 1mA and should a spike occur, it would not recover fast enough.
Note: (Since the outputs of the IC's are current regulated, R2 and R7 are really not needed.)
The second part of the circuit in the red box is the amplifier part. Here signal is fed into C4 and carried to the +ve input of the 741. R3 and R4 keep the capacitor from charging up in signals with only one side (ie the signal waveform is not swinging from + to -). R5 and R6 control the gain of the circuit by varying the -ve feedback. Once again the output is buffered by the transistor setup.

APPLICATIONS

This circuit is a UNIVERSAL pre-amp and can be used in almost any circuit where the signal is very small. eg. Microphones, recievers...

TESTS

This circuit consumed less than 10mA at 12V. It is a very stalbe circuit.

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#476 From: "mrdavesimon" <simon001@...>
Date: Wed Jul 31, 2002 7:11 am
Subject: Re: C9018 Transistor mrdavesimon
Send Email

--- In home_electronics@y..., Advantis <advantis@g...> wrote:
> Hello
>
>   Does anyone know some equivalence to the C9018 transistor? I wan
>   unable to find any data on the Net about it.
>
> --
> Best regards,
>  Advantis                          mailto:advantis@g...


Hi:
I sent you two links to two different sites that will give you all
the info you should need.
   Simon001

Reply | Messages in this Topic (2)

#477 From: Paul Perry <pfperry@...>
Date: Wed Jul 31, 2002 12:32 pm
Subject: Re: [Electronica] Re: C9018 Transistor pfperry@...
Send Email

>>   Does anyone know some equivalence to the C9018 transistor? I wan
>>   unable to find any data on the Net about it.

Probably a 2SC9018, the Japanese often only put the last part of the number
on the transistor!

paul perry (Frostwave analog fx manufacturer)

Reply | Messages in this Topic (1)

#478 From: "Nicolae Sfetcu" <amacom@...>
Date: Wed Jul 31, 2002 6:45 pm
Subject: Rain Detector nsfetcu
Send Email

Rain Detector

This circuit uses a sensor made of a small piece of etched PC board and a simple SCR circuit to detect rain and sound a buzzer. The SCR could also be used to activate a relay, turn on a lamp, or send a signal to a security system.

Schematic

Parts

Part	Total Qty.	Description	Substitutions
R1	1	1K 1/4 W Resistor
R2	1	680 Ohm 1/4 W Resistor
D1	1	1N4001 Silicon Diode
BZ1	1	12V Buzzer
S1	1	SPST Switch
SCR1	1	C106B1 SCR	106CY
SENSOR	1	See Notes
MISC	1	Board, Wire, Case, PC Board (For Sensor)

Notes

1. The sensor is a small piece of PC board etched to the pattern showen in the schematic. The traces should be very close to each other, but never touching. A large spiral pattern would also work.

2. Make sure to use a loud buzzer.

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#479 From: "Nicolae Sfetcu" <amacom@...>
Date: Thu Aug 1, 2002 8:06 pm
Subject: Simple Phone Tap nsfetcu
Send Email

Simple Phone Tap

This circuit is extremely simple, therefore there is less chance of any problems. It can be placed anywhere on the phone line and it will record any conversation on any phone on that line.
Schematic

Parts

Part	Total Qty.	Description	Substitutions
R1	1	470 Ohm 1/4 Watt Resistor
R2	1	1K 1/4 Watt Resistor
R3	1	100K 1/4 Watt Resistor
R4	1	6K 1/4 Watt Resistor
C1, C2	2	0.01 uF 100V Ceramic Capacitor
K1	1	24VDC Reed Relay
MISC	1	Wire, Headphone Plugs, Phone Plug Or Alligator Clips

Notes

1. To use the circuit, simply connect it in series to the phone. Then plug in the recorder. It will start recording when the phone is picked up.

2. The values of R1 and R2 may have to be adjusted, depending on the characteristics of the phone line it is connected to (they vary). If the R1+R2 combination is increased sufficiently (try 2.47K) then the circuit can be connected in parallel with the line, thus covering all attached devices.

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#480 From: Jack Emery <jackemery@...>
Date: Fri Aug 2, 2002 8:05 pm
Subject: Re: [Electronica] Simple Phone Tap jackremery
Send Email

Thanks a Bunch Jack Emery

----- Original Message -----

From: Nicolae Sfetcu

To: Y: Electronics

Sent: Thursday, August 01, 2002 4:06 PM

Subject: [Electronica] Simple Phone Tap

Simple Phone Tap

This circuit is extremely simple, therefore there is less chance of any problems. It can be placed anywhere on the phone line and it will record any conversation on any phone on that line.
Schematic

Parts

Part Total Qty. Description Substitutions

R1 1 470 Ohm 1/4 Watt Resistor

R2 1 1K 1/4 Watt Resistor

R3 1 100K 1/4 Watt Resistor

R4 1 6K 1/4 Watt Resistor

C1, C2 2 0.01 uF 100V Ceramic Capacitor

K1 1 24VDC Reed Relay

MISC 1 Wire, Headphone Plugs, Phone Plug Or Alligator Clips

Notes

1. To use the circuit, simply connect it in series to the phone. Then plug in the recorder. It will start recording when the phone is picked up.
2. The values of R1 and R2 may have to be adjusted, depending on the characteristics of the phone line it is connected to (they vary). If the R1+R2 combination is increased sufficiently (try 2.47K) then the circuit can be connected in parallel with the line, thus covering all attached devices.

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#481 From: "Nicolae Sfetcu" <amacom@...>
Date: Mon Aug 5, 2002 3:19 pm
Subject: Telephone Hold Button nsfetcu
Send Email

Telephone Hold Button

Although a hold feature is standard on most new phones, a lot of us still use the origional bell phones. Those of us that require a hold feature will find this circuit very useful. It is easy to build, and is compact enough to be installed inside the phone with no real problem. It is also powered by the phone line itself, eliminating the need for batteries.

Schematic

Parts

Part	Total Qty.	Description	Substitutions
R1	1	1.5K 1/4 W Resistor
R2	1	1K 1/4W Resistor
D1	1	1N4002 Silicon Diode	1N4003, 1N4004, 1N4005, 1N4006, 1N4007
SCR1	1	C106Y SCR
LED1	1	Red LED	Green LED, Yellow LED
S1	1	Normally Open Push-Button Switch
MISC	1	Wire, Board, Case (If Used)

Notes

1. To place a call on hold, simply hold down the button while hanging up the phone. To take a call off hold, just pick up the phone, or any extension.

2. Even though this is a simple circuit, you may have to check with your phone company before use.

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Notes:

Phone Busy Indicator

Schematic

Parts:

Notes:

Null Printer Adapter

Circuit operation

Circuit diagram

Another proposed circuit

Ringing Phone Light Flasher

Schematic

Parts:

Notes:

Cut Phone Line Detector

Schematic

Parts

Notes

Rain Detector

Schematic

Parts

Notes

Simple Phone Tap

Parts

Notes

Simple Phone Tap

Parts

Notes

Telephone Hold Button

Schematic

Parts

Notes