Creating a new audio amplifier part 3.

My youngest son and I went downstairs to the workshop / garage this evening and started removing bits from the receiver. He had some fun. I found that the ganged switches are soldered to the circuit boards these will be a little tricky to remove without damaging them. Luckily the switches are also mounted onto an angled piece of pressed steel and so I should be able to mount them without a circuit board.  The RCA sockets on the back panel were also soldered to the board but these should be easy enough to reuse. We dismantled the front panel and I believe it won’t be too tricky to mount a piece of flat aluminium on top of this front panel.

One electrical problem I have come across is (as I have previously mentioned) the power supply that exists is delivering too much voltage for hte LM1875’s but it was pointed out to me today by Rod Elliot that I could use the LM3886’s instead. This would give me a more powerful amplifier but I would have wasted money on the LM1875’s. I could also use another transformer I have but this is about 60VA and would mean a reduced power output for the LM1875’s – this probably doesn’t really matter as most of the time the amp will be driving headphones.  It’s just that once I noted that I could use the more powerful amplifiers chips – I just want to!  It seems ridiculous (but frugal) to use such a big case for such a low powered amplifier.

So I have a conundrum. Making things worse is that apparently there are fake LM3886’s being sold on ebay – I could get a pair for about $12 (free shipping but possibly fake (why would you bother?)) or from element14 for 12 + 12 shipping or from Mouser from $19 + $39 shipping!

Part1, Part2, Part4

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