Amplifier Fun.

[Yorkie]

Nice neat breadboard layout Joe in the final version, and neatly drawn circuit too!

Lots of fun on a shoestring, as befits the austere times in which we live, which takes me back to my childhood to which I suspect I'm slowly regressing - ration books and what not!

I've been toying with making a simple valve amp to sprag onto the Jasonkit FM tuner (like the one you bought), which awaits attention. I came across a design for a 'Miniature Power Amp' in Oct 1964 PW for which I have all the bits to hand including the valves, in my 'spares box' (or more accurately, 'boxes'!). It appeals because it uses twin triode ECC82/83s - in effect, two valves in one envelope. It called for an external power supply and I found another design (for a one-valve 2.5 Watt amp using an ECL82), in Aug 1970 Radio Constructor which had a simple built-in power supply. I therefore lifted the PSU from that design and tagged it onto the PW design, which has a neat tag-board layout.

I doubt I'll get round to building the amp any time soon, and I'm not offering it as the best of all possible designs. I know that ECC82/83 valves have become expensive and wouldn't be everyone's first choice of valves, but as I have them to hand, it isn't an issue for me - the amp will be cost-free. (At the time the article was written, ECC82/83 valves were six shillings, (not as cheap as it may sound today, but cheaper than OCC44 transistors and the like, at ten shillings).

I've attached the article of the PW design, and the circuit as adapted from Aug 1970 RC Mag to include the PSU, which might be of passing interest. The use of a solid state rectifier (originally contact-cooled metal rectifier) rather than a valve, would enable a small chassis, one less valve, and hence, less current required from the small mains transformer that I have to hand.

Hope that's of interest.