... I would add a small pico cap as a filter, to pull off some of that noise. I think what youre hearing is some oscillation of the transistors. Try some feed...
I don't generally recommend messing with radioactive substances! I have heard of people burning the mantles to concentrate the thorium in the ashes but I've...
Hi Charles, I tried to email you directly, using the email address at your website, but the message was bounced back. Then, I noticed the forum option at the...
Our email was misdirected last weekend but it should be working now. I've been moving all our websites to our own server but somehow managed to break the...
Greetings all ... I am in the process of rebuilding a '72 Alfa Romeo and I want to add a circuit to "chime" if the key is left in the ignition or if the head...
Years ago I added an audio alert to an electronic scale and, much to my surprise, it sounded exactly like the chime on the typical airplane telling you to...
Hi Charles, Thanks for your quick response. If it's not much trouble, I'd appreciate you adding the schematic to your website as you suggest. Thanks, Eric ......
I just added it below the two gate circuit. I used a '4069 for all four gates and it seems to work nicely. ... appreciate ... the web. ... forum ... circuit, ...
I came up with a circuit that sounds pretty good. See the bottom of http://www.techlib.com/electronics/noisemakers.html. I hope I drew it right; it seems like...
Thanks again, Charles. I will definitely put that circuit to good use sometime soon. BTW, for the 5v beeper you show in the original, what kind of beeper is...
I don't know where it came from originally but I'm guessing off an old computer board. I just looked at what I have now and they are all piezo or magnetic...
While I was thinking about it, I thought I would run this one by you, Charles, while I had a chance. I have a cheap wireless thermometer for which I would...
Do you know the frequency? I might start by simply adding length to that wire. If the frequency is low, say 49 MHz, a longer wire might be all it takes. How...
Hi Charles, I know, this initial info was a little vague. The model I have is an Acurite model 00782. There are a lot of advertisements for it around the ...
Wow, only $10; I'll have to stop by Walmart later! I guess the proper wire length for 1/4 wave is about 7 inches so I would first try maybe 6 inches on both...
... Yeah, it's a nice little unit for the price. Reads both indoor and outdoor temperatures. Right now, I have the transmitter in a location that pretty much...
I was just looking at my circuit on the web when I realized that the two unused gates could be used to make another audio oscillator for another frequency....
Hi Charles ... sorry for taking so long to get back to you but thanks very much for the info ... the circuit looks perfect... I will proto it and get back to...
Hi Charles ... you Sir are a genius .... I've constructed the circuit as per your schematic and it sounds perfect. I don't even have to play with the chime...
Well, thanks for the compliment but I actually discovered that approach by accident when I added a little beeper to a train scale I was working on. Imagine my...
The wireless thermometer is nearly complete. I now have a housing against solar radiation and for weather protection, so I can place the transmitter where I...
I think I might try NiCad batteries since they are forgiving of overcharge; they just get warm. There are some pretty cheap panels out there. For example: ...
I have an old Oregon Scientific wireless thermometer, the AAA batts last a couple of years or more, lithiums would last even longer so I question the return on...
You have a point. A couple of D cells would probably hold up for their typical shelf life of a decade or more. ... last a couple of years or more, lithiums...
Hi Charles, I need your help in building a message board to show some message on led matrix, which I can change with the help of computer's serial port. ...
