Pictures here: Tim's GainClone
Built with briangt's kit and standard parts. I had a bit of a problem with DC offset at first, but fixed (below 1.5mV) with an electrolytic in the feedback circuit as suggested in the app. note.
I was hoping the three cases would give good hum isolation, but there is some hum (only audible with my ear to the speaker), and some pickup of clicks from other appliances in the room - I probably didn't take enough trouble to twist power wires and I didn't use shielded signal cables. I also didn't ground the outer cases (they only receive DC from the power supply - this may be unwise and I'll probably change it as I suppose there's a remote possibility that AC could short to a DC wire...
But the sound - now that the DC offset is fixed - is superb. Very accurate, very listenable, no complaints.
tim.
Built with briangt's kit and standard parts. I had a bit of a problem with DC offset at first, but fixed (below 1.5mV) with an electrolytic in the feedback circuit as suggested in the app. note.
I was hoping the three cases would give good hum isolation, but there is some hum (only audible with my ear to the speaker), and some pickup of clicks from other appliances in the room - I probably didn't take enough trouble to twist power wires and I didn't use shielded signal cables. I also didn't ground the outer cases (they only receive DC from the power supply - this may be unwise and I'll probably change it as I suppose there's a remote possibility that AC could short to a DC wire...
But the sound - now that the DC offset is fixed - is superb. Very accurate, very listenable, no complaints.
tim.
An externally hosted image should be here but it was not working when we last tested it.
Hey Tim-
Really good idea. I like the visual effect and the pwr supply isolation.
May I suggest grommets around the holes between enclosures? I would hate to see such a great project go up in smoke due to skinned wire.
Look for "caterpillar grommet" at your local electronic store. I oversize mine a tad bit to keep outward pressure on it and I usually put a dab of silicone or hot glue to hold it in place.
Really good idea. I like the visual effect and the pwr supply isolation.
May I suggest grommets around the holes between enclosures? I would hate to see such a great project go up in smoke due to skinned wire.
Look for "caterpillar grommet" at your local electronic store. I oversize mine a tad bit to keep outward pressure on it and I usually put a dab of silicone or hot glue to hold it in place.
Thanks for your comments. You're right about the grommets - I couldn't find the right size at Maplins, so I used heatshrink to add a layer of protection over the power supply wiring. I did work quite hard to d-burr the holes, but you can't be too careful with power wiring.
Regards,
tim.
Regards,
tim.
Upupa Epops said:Nice work, but isolation of transformer's hum by aluminium have low efficiency.
Any good ideas about how to simply improve the hum isolation? I thought I might put a steel mesh cage around the transformer (mesh is cheapish at the local DIY store). I could also twist the power wiring that passes across the top of the transformer...
tim.
timbarnes said:the amp picks up cell phones from quite a distance.
tim.
Look like you may be able to patent this
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