10w Class A IRF510 Amp

So I like to learn by doing, and it was time to learn about amps, biasing, mosfets and all other things, I thought what better way to learn than by building something and hopefully not ending up with Einstein hair or the house burning down.

I did a scour of the web and found a ton of schematics all pretty similar, claiming anywhere from 5w out to 30w out from a pair of IRF510 Mosfets. So far i have managed to get 10w out of a pair, which is the biggest amp i have build thus far in my limited time in radio and electronic construction.

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This is the schematic I used, yes i drew it up in LTSpice and did some simulations and no for those wise people that bias network wont work like that in Spice, I just used a voltage source connected to the 22ohm resistor for that.

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This is the amp as constructed with scope and signal source connected.

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10w out on the power meter, would be nice to claim 100w HIHI.

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Its pulling a little current, I will be playing with the bias to bring that back to say 1.5a, its happy and stable there, no thermal run aways or anything, but as you will see there is slight distortion on the wave form.

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A slight bit of distortion, that i will clean up with bias.

The next things to learn about are temperature compensated bias just so it does not run away and explode and some feedback to help with IMD etc. I have had a heap of fun with this little project and have learned a lot, still a long way to go, to get to the 20w I am aiming for, and i doubt that i will get close to that figure with this amp, but, its a step in the right direction and 10w is the biggest i have achieved so far,

Cheers,

Rob.

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