DHT Heater using VCCS - PCB or Kit (Possible Group buy)

What people are working on at the moment
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IslandPink
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#46

Post by IslandPink »

They are quite low - 4.2V at 0.325A
( Also centre-tapped so you can run them at 2.1V @ 0.65A )
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#47

Post by IslandPink »

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Andrew
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#48

Post by Andrew »

You going to Owston, Mark?

Andrew
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#49

Post by IslandPink »

Yes....Saturday ... do you feel a prototype coming on ?
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#50

Post by Andrew »

Well I was thinking I might be ale to bring soemthing down. Could be just some raw PCB for you to build up, could be something to try on the day, dunno what suits best?

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#51

Post by IslandPink »

OK - I don't want to force you into making a PCB prematurely .
In that case trying something (prototype) on the day makes most sense.
It will however be hard to judge in that kind of environment on the Saturday .
If you already have some PCBs, then I would take one away and try out in more suitable circumstances.

Does that make sense ?

ps. For info, I'm feeding your V-reg ones from 6V toroid : most likely 7V AC ; for 4.0 V out ( sufficient ) .
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#52

Post by Andrew »

OK, I have one built that is as final as it's going to be at this stage, I'll bring it down for you to try, either on the day and/or to borrow for feedback.

Here's the spectrum on the 200mV scale, temp of the heatsink reads 45 degrees C above ambient for 5V in 3.7R, so 1.35A.

It will need to be set for whatever voltage you need; its just a resistor change.

cheers,

Andrew
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#53

Post by IslandPink »

That looks excellent .
If you could adjust it to give something from 4.0 to 4.2 volts before Owston, that would be great . Also if you can give it a few hours steady running so the caps can form-up that would be good, although of course it should be less of an effect on this high-z source than on the voltage-regulated ones . I could hear a distinct improvement in the driver board I've just made, in 3-4 hours, which I attributed to a combination of the 4P1L's warming up, and the filament supply caps forming - not sure which was most significant in that . There wasn't much else that had to run-in .

Edit : just worth asking that I can get a clean 4.2V DC out if I feed it with ~7V AC in, is that OK ?
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#54

Post by Andrew »

IslandPink wrote:
Edit : just worth asking that I can get a clean 4.2V DC out if I feed it with ~7V AC in, is that OK ?
Let me check on that.
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#55

Post by Andrew »

All set Mark, the test board is ready and set for 4.2v, you should be OK with 7v AC in, I can explain all on Saturday.

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#56

Post by IslandPink »

Excellent !
Can somebody bring a soldering iron, please ?
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#57

Post by Andrew »

IslandPink wrote:Excellent !
Can somebody bring a soldering iron, please ?
You bringing the amp then?

Andrew
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#58

Post by IslandPink »

Oh yes !
If there's one of the new boards, it ought to be possible to have it running at some stage with one V-reg board and one I-reg board, and if I bring a good mono record, we can compare the sound quickly by adjusting the volume pots ( two ) on the left and right channels .
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#59

Post by Andrew »

Could be interesting...not done that experiment.

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#60

Post by IslandPink »

Got the DHT supply in place and had about an hour listening so far, Andrew .
Just one ( left ) channel, obviously .
It does seem to fill out the upper bass tone , so far.
The Stranglers sounded good !
Not sure if I've lost something, but I'll update you in the next day or two how it goes as I do more running/listening .
"Once you find out ... the Circumstances ; then you can go out"
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