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

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

Post by Nick » Sun Jun 10, 2018 11:14 pm

Resistance isn't futile it's V / I.

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

Post by IslandPink » Sun Jun 10, 2018 11:24 pm

Thanks.
Another fail from Google !
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Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by Andrew » Tue Jun 12, 2018 7:52 am

Mark, I've got a also got few spares, if you need them.

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

Post by IslandPink » Tue Jun 12, 2018 8:32 am

Thanks - another 8 would be handy for two more boards. Will you be at Owston ?
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Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by RhythMick » Tue Jun 12, 2018 8:44 am

I bought 3 syringes of thermal grease ... no idea why, I can't see me getting through 1.

https://uk.rs-online.com/web/p/thermal- ... 3732323926

I'll bring the other 2 to Owston, anyone who can use them is welcome. Actually I wonder what other surplus I can dump on somebody, I mean I wonder who else might benefit from my treasure trove of goodies ...

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

Post by Andrew » Tue Jun 12, 2018 9:35 am

IslandPink wrote:
Tue Jun 12, 2018 8:32 am
Thanks - another 8 would be handy for two more boards. Will you be at Owston ?
Planning to be there.

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

Post by Andrew » Thu Jun 14, 2018 7:51 pm

Those remaining are:

Neal : 4 x large
Michael L 2 x large

Neal are you planning on being at Owston?

thanks,

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

Post by RhythMick » Sat Jun 30, 2018 1:45 pm

Experimenting with something separate, my caps were all at my brothers so I used one of the 5600uF caps supplied with the DC boards. So THAT's what a blown capacitor looks (and smells) like.

No harm done and all valuable lessons. Andrew could you give me a link to the ones supplied please so I can check the datasheet and see where I went wrong ? I take it any 105degC 16v 5600uF cap will be fine ? I'll get some spares too.

This one ok ?

https://uk.rs-online.com/web/p/aluminiu ... s/7396800/

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

Post by Andrew » Tue Jul 03, 2018 7:31 am

Hi Mick,

I wont' ask what happened. You really need Panasonic FR Series, high ripple, not cheap but worth it.

cheers,


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

Post by RhythMick » Tue Jul 03, 2018 7:58 am

Thanks Andrew

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

Post by RhythMick » Fri Aug 24, 2018 8:45 pm

Ok I've built all my boards for the new amp (4 small, 8 large) and am testing them now.

All good, but one board takes forever to reach the value. The others are all perhaps 20 seconds, but this one I timed (patiently) and recorded the values over a lengthy period. Aiming for 5v, after about 5 minutes it's at 4.78v, about 90 minutes later it gets to 5v. It seems to stabilise eventually.

Any clues where to look for issues?

UPDATE: when targeting 1.5v or 2.5v it's fine, just 5v it struggles with. Also the led is lit green, though not bright, whereas I can't tell the others are on.

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

Post by IslandPink » Fri Aug 24, 2018 9:20 pm

RhythMick wrote:
Fri Aug 24, 2018 8:45 pm

UPDATE: when targeting 1.5v or 2.5v it's fine, just 5v it struggles with. Also the led is lit green, though not bright, whereas I can't tell the others are on.
Interesting. I can't offer the advice you need, but I remember quizzing Andrew and DavetB about how dim the green LED was on one of my boards when I had ( another) problem - we all agreed that it's barely visible in daylight - so if you have one brighter , maybe that is significant.
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Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by Dave the bass » Fri Aug 24, 2018 10:21 pm

Yups, its used as a voltage ref IIRC, not an indicator as such.
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Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by RhythMick » Sun Aug 26, 2018 2:40 pm

No actually even targeting 2.5v it's slow to rise, just less noticeable. After about 10 minutes it gets to 2.44v. Temperature of both D44H11 & LD1085P are stable (around 44 & 54 deg C respectively, bolted to a 3mm copper sheet).

To be honest I could live with it, but I don't like things not being right.

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

Post by RhythMick » Sun Aug 26, 2018 6:06 pm

Problem solved.

I realised the 2 boards I want happy with were the first board I built, and I'd never built a PCB before that. Sure enough there were some joints I was less than happy with. Reworked those and all is well.

I've now built 24 of these boards (16 large, 4 small) and I'd like to think I'm much better now. Think that proves it. All have been tested with resistors simulating 26, 71A & 45 heaters.

Thanks for the support and advice.

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