I blame the present lock down for getting me back into tube/valve technology. Having stopped work and being stuck in the house meant I needed to do something that used my time and I hate gardening.
I picked up an old PYE valve radio prior to the restrictions so had some fun cleaning and repairing the case for that. Next I ordered some old military cold war gear from Ebay and was lucky enough to get that before the seller shut shop for a time. It contained sub miniature 6021 and 5840 wired valves, so had a look on the web for circuits, came across a couple of small guitar amps using the 6021. So also learning to use Kicad I did a board design with some negative feedback and had 5 boards made and built me some small amps.
The first one used a Hammond 125B output transformer, The next one used a small home made PP output transformer from recycled laminations but lacking frequencies under 200Hz, so with slightly larger transformer wound a couple more to make a simple milliwatt stereo amp.
At this stage the bug seems to be with me, I have some EL84's from Ukraine on the way, but also fancy making an amp with some TT15 valves. I am lucky in that I can make a basic aluminium/steel chassis in the garage if required having a few machine tools.
It is strange that I have not listened to as much music as I have recently on my small amp, typical as my hearing is getting worse with age.
Adrian
I picked up an old PYE valve radio prior to the restrictions so had some fun cleaning and repairing the case for that. Next I ordered some old military cold war gear from Ebay and was lucky enough to get that before the seller shut shop for a time. It contained sub miniature 6021 and 5840 wired valves, so had a look on the web for circuits, came across a couple of small guitar amps using the 6021. So also learning to use Kicad I did a board design with some negative feedback and had 5 boards made and built me some small amps.
The first one used a Hammond 125B output transformer, The next one used a small home made PP output transformer from recycled laminations but lacking frequencies under 200Hz, so with slightly larger transformer wound a couple more to make a simple milliwatt stereo amp.
At this stage the bug seems to be with me, I have some EL84's from Ukraine on the way, but also fancy making an amp with some TT15 valves. I am lucky in that I can make a basic aluminium/steel chassis in the garage if required having a few machine tools.
It is strange that I have not listened to as much music as I have recently on my small amp, typical as my hearing is getting worse with age.
Adrian
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