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Update
While I was on a roll I decided to make a PCB for the PSU.
I had half a 160 x 100mm board left over from the regulator project and a pair of PCB's just fit.
Because I am fitting the PSU board in my existing external case it ended up an unusual shape due to space restrictions, but it still follows Jim's schematic. The other board is for my second deck which uses the same case, but it doesn't have the control switches in the roof and the on/off button is in a less restrictive position so there is much more room.
I need to test the output of this next and the regulator when its connected to it, before hooking up to the deck.
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Genuinely fantastic!
Looking forward to hearing about your impressions of the mod.
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Update
Thanks Jim, here are the measured results for the unloaded PSU.
On the left is the output from the stock Technics transformer (UK version).
In the centre is the output from the PSU board containing full-wave rectification and smoothing.
And on the right is the output from the regulator board.
I will also check the regulator output under load later.
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Those are all spot on! Wonderful!
It's a nice compact PSU circuit board. I like it.
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Update
All back together - When allowed to warm up, the voltage settled at a slightly higher level than the initial quick test I did without a heat sink.
It starts at 20.4v after a couple of seconds is 20.5v after 10sec is 20.6v and after a minute is 20.7v were it remained even after several hours.
When running at either 33 or 45rpm it remains a constant 20.7v, if considerable finger pressure is applied to the rim of the rotating platter the voltage remains at 20.7v. If you keep increasing the pressure, eventually the voltage drops off to around 18v but you are talking a lot of pressure and just before the point where the motor stalls.
On start up for 33rpm the voltage drops to approx 20.5v for half a second, but this is inconsistent and on some occasions did not drop at all. On start up for 45rpm the voltage drops are also inconsistent some times as low as 19.2v sometimes around 20.2v again for about half a second. If you do quick start stops the drop seems larger, if you allow a pause, about the time to load a record the drop is smaller, maybe the capacitors are playing catch up?
Also when stop is pressed there is a momentary drop of 0.1/0.2v as the brake is applied. For all these tests I had the stock platter, a 180g record and a 800g brass puck in use.
All in all I think this power set up is pretty stable.
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That all sounds as expected, Ken. Well done, you have a unique looking and powered deck there.
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Guys I think this zener should be pretty close to what is needed for a single reference part
http://gr.mouser.com/ProductDetail/R...svwIS4Vw%3d%3d
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dimkasta - someone would have to confirm spec is ok, but that part is a surface mount device.
They can be soldered by hand but its a pain and my board would have to be canged so it could be soldered on the underside as its a single sided PCB I have produced.
Don't know how you would use them without a PCB?
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It might be SMD but it is a two terminal device so it should be pretty easy to solder. It's 5mm in length so t should be easy to handle.
Oh and you can very easily solder scrap wire cut from resistors to it and basically make it a through-hole component
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By the way, I ve been playing around with the preregulator thingy and I came up with this schematic
317_prereg.jpg
Basically I added the filter caps, the protection and thermal drift diodes and selected a few values for components. Oh and R3 should be 100R.
Any comments?
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