Wow! Check out the latest rig from PY2OHH, the Wizard of Sao Paulo,
http://py2ohh.w2c.com.br/trx/pititico/pititico.html
Our book: “SolderSmoke — Global Adventures in Wireless Electronics” http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20
Nice! Now I feel compelled to build this. Here’s another ultra simple circuit I ran across on YouTube the other day (from Make magazine I believe). Super simple FM transmitter: https://www.youtube.com/watch?v=MMgzUGBfXiE&list=FL2K8XCApwENL4mlwOAyE9gA&feature=mh_lolz
Egad! No output filter?! But then I guess it would no longer be “Super” and only a plain “Minimalist”. Like Peter VK3YE, I am somewhat askance at the 700 mW claim. Be that as it may, Paulo certainly has a fab. web site for ham HB. 73…….Steve Smith WB6TNL “Snort Rosin”
Bill, I actually just built and tested this circuit. The TX gave me about 1/4 watt and the RX didn’t work at all for me. Not sure what’s wrong. I posted what I did on my blog if you’re curious: http://wf7ihomebrew.wordpress.com/2014/04/11/py2ohhs-pititico-and-14-watt-but-no-rx/
Not sure if you read the older blog comments but just letting you know the RX works now too. I was just a little confused as to what I was seeing and I had to use an amplified speaker. I emailed Miguel and he agreed that the audio is a little weak (and he uses an ~500 ohm impedance telephone earpiece for his, which I don’t have). I’ve been updating my blog with the evolution of the little circuit and put a demo of it on YouTube as well.
A little older article… but I just rebuilt my older versions I made last year. With a simplified bandpass filter ( a PI filter with series capacitors both on input and output )… I finally got rid of the annoying AM broadcast band interferences. I removed the 1N4148 from the audio output and the audio is a lot stronger. The clicking sound doesn’t seem to be much diferent with or with ought them. The power output was initially around 1W, but the transistor was heating up quite a lot ( 2N2222 ), so I reduced the output capacitor from 470pF that I was using to 330pF. Now I still get 550mW of power. The only thing I’m not so sure about working right is the frequency offset, as it doesn’t seem to be as I would like it to be. 73… great little TRX.
I saw a video of DX Explorer’s build of the TX side of it ,it registered a little over 700 milli watts ,,I built a version of it but could not get it to receive and Tx had a bit of a chirp nice little fun project .