Quote:
Originally Posted by ms660
Re: Post 26, sorry to do this but in the original the 100nF was across the supply that directly feeds the Osc, the Osc in your circuit is only de-coupled by an electrolytic, electrolytics are not the best de-couplers for RF, a suitable ceramic capacitor would be best placed across the electrolytic in my view.
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No need to apologise Lawrence.
It will be evident that my practical skills and abilities have always far exceed my rather basic technical skills, so any advice is always welcome.
I have a history going back decades, of making 'workmanlike' homebrew projects which look well turned out and nice on a shelf, but don't work!
Hence, there's no point in my building something which either contains redundant components which serve no useful purpose, or conversely, degrading the performance by leaving out components which would improve the performance. That's especially so when posting on a forum such as this, where other members might wish to replicate the project, as was so with the Guy Fernando Converter.
I simply used the information that Derek ('coopzone') provided in his earlier post outlining what he did to adapt the transmitter part of Guy's original design. You'll note that Derek added the 100µF electrolytic to reduce hum from his 'wall wart'. In the updated circuit above, I just reinstated the 100nF cap (C1) to where it was in Guy's circuit.
Are you saying that C1 would be better positioned in parallel with C8 - the 100µF cap, and if so, in 100nF a suitable value?
to quote Derek's post:
I built everything to the right of R1 470k (including the resistor; I later changed the value to a 100k as the volume was a bit low)
Next I permanently connected R2 1k to ground (-ve line from battery), so as to enable the transmitter all the time.
Next I changed the values of C4/C5 to 150pf to change the frequency, as the original values just happened to be very close to a local station. You may not need to do this step.
Next I added a 100uf cap and a 470ohm resister across the +ve/-ve ( for the cap) and the resistor in series withe the +ve. This reduces the voltage to the circuit and reduces the ripple (and hum) caused by the low quality plug-in-the-wall PSU I used. This power supply was 9v unregulated and was also used to power the Bluetooth/radio/mp3 module.
End quote.
Thanks once more for your interest and input.
Dribble 'Confused, of Cottingham'
