I'm having trouble finding too much technical information about Peltier thermoelectric devices. I have a potential application in mind and these devices seem...
Thanks for your post. I'll see if I can answer these one at a time. Maximum ripple should be about 10% or less. A rectified AC power supply is ok as long as...
Hi, Tom...I just finished by first board and am ready to test it. The other two are almost finished, too. It went together very easily and quickly. The only...
Tom, I found the answer to my question. There are wiring diagrams for all stepper configurations at http://www.flashcutcnc.com/html/con_step_mot.html as well...
Tom, I am testing my first board. The 5V is fine. When I went to adjust VR1, I couldn't get the voltage over about 2.7, with J3 shorted. Then I discovered I...
John, Just to clarify things, 1A and 1B are the connections for one phase, 2A and 2B is the other phase. For series: 1A - blue 1B - green connect red & yellow...
John, The first PIC is probably fried, but I don't think it would have damaged anything else. I am beginning to suspect that some PIC's that were sent out a...
Thanks for the clarification! I'm not ready for more speed yet. I don't use my mill in a production environment and I have plenty of other things to keep me...
Well, it worsks at least mostly. My first board has been hooked up to a motor and seems to work just fine. The half-current does not work, but probably will...
It is normal for the A3977 to get warm - and warmest when the motor standing still. I'm glad the heatsinks seem to work. I haven't tried the heatsinks...
Just got a chance to check the PIC sent with my PCB's and all three are 12F675"s. Do you need to send me three 12F629's? If you need my address please request...
Just getting ready to populate my boards and had a question on component orientation. 1. Is there a required orientation on ceramic caps? 2. How about...
Polarity is not important for the ceramic caps and resistors. Electrolytic caps have a stripe with a minus sign near their negative lead. On the THSTEP25,...
Wrapping up the A3977 PCB project and have a few more questions: 1. Assume the pads with drilled holes on 6 of the pins on A3977SED are there for scope...
i have an unregulated power supply... transformer, bridge rec., capacitors. it was used for the stepper motors im using in my project. problem is it puts out...
1. The 6 holes are "vias" that make electrical connections between the A3977 pins on the top of the PCB to the traces on the bottom. Two are connected to VBB...
An unregulated supply is fine, but the voltage must be well below 35 volts. If the transformer has multiple taps, you may be able to re-wire it for a lower...
Getting ready to start up my THSTEP25 and have the following questions: On adjusting the "Internal PWM Current Control" for Itrip reference voltage. What and...
i have just powered up my boards. set all the voltages etc. all is fine. but cannot get my motors to run. not sure if its the boards or my comp. / cnc program....
Ok... The Itrip reference voltage is "Vref" given in the THSTEP25 datasheet on page 6: Vref = 1.6 X (desired current) The "desired current" is the stepper...
The first question is, does the motor "lock up" and hold position when the power is on? If so, then check your CNC software setup. If the motor does not lock...
Tom, What's the status of replacement PICs? You will remember I fried one of my original 12F675s by puting it in backwards, so I need to replace it with...
Hi Tom, I have assembled 3 boards, and two work perfectly (except for the problem with the PIC). The 3rd board has a different challenge. 5v is correct, and...
Hi Tom, I have assembled 3 boards, and two work perfectly (except for the problem with the PIC). The 3rd board has a different challenge. 5v is correct, and...
Sorry for the delay in getting back to you. First, new PIC's should be on the way soon. Meanwhile - With no PIC or a defective one, the digital inputs such as...
Hi, More info...the board seems to be switching between enabled and not, since I can turn the motor shaft with my fingers in step with the chatter. Is this a...
Hmmm... sounds like thermal shutdown. The chip disables itself when it gets to a certain temperature and then enables again when it cools a few degrees. ...
I'm making some progress. I disconnected the motor and compared readings between two boards, a good one and the one with problems. The problem board did not...
I admit that those readings are puzzling. You should be getting very high resistance readings (MegOhm or KOhm) between the power pins and the phases. On your...
