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

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#1006 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

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#1007 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by IslandPink »

Thanks.
Another fail from Google !
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#1008 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by Andrew »

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

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#1009 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by IslandPink »

Thanks - another 8 would be handy for two more boards. Will you be at Owston ?
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#1010 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by RhythMick »

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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#1011 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by Andrew »

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.

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#1012 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by Andrew »

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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#1013 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by RhythMick »

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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#1014 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by Andrew »

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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#1015 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by RhythMick »

Thanks Andrew
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#1016 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by RhythMick »

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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#1017 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by IslandPink »

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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#1018 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by Dave the bass »

Yups, its used as a voltage ref IIRC, not an indicator as such.
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#1019 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by RhythMick »

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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#1020 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)

Post by RhythMick »

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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