DHT Heater using VCCS - PCB or Kit (Possible Group buy)
#1036 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
There's two more large smoothing caps on the "big" boards to deal with the extra incoming AC ripple, but if you're not using them for high current heaters, its just wasted money.
The "small" ones will do 300B and everything downwards, the big ones are really for 2A3, nothing will do a GM70 without serious hacking.
Andrew
The "small" ones will do 300B and everything downwards, the big ones are really for 2A3, nothing will do a GM70 without serious hacking.
Andrew
Last edited by Andrew on Sun Feb 03, 2019 12:23 pm, edited 2 times in total.
Analogue, the lost world that lies between 0 and 1.
#1037 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
I'd like 4 pcbs please Andrew. Also happy to buy any components for the boards if you have surplus stock you want to get rid of.
#1038 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
The "small" ones will do 300B and everything downwards, the big ones are really for 2A3, nothing I have will do a GM70 without serious hacking.
Andrew
Andrew
Analogue, the lost world that lies between 0 and 1.
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#1039 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
I thought mine were reasonably standard ?
GM70 & GK71 heaters the same (or very similar).
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G-Popz THE easy listening connoisseur. (Philip)
#1040 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
No, that's all yours and Mark's own work, Phil. I disown it.
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#1041 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
But seriously ( folks ) do you have a residual gripe about the GK-71 application ? - after all, it seemed to be merely a matter of feeding it with a 24V SMPS and making sure one or two caps on the board were 35V rated, as I remember ( and the heatsink up to scratch ) ?
"Once you find out ... the Circumstances ; then you can go out"
#1042 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
I'd like 4 pcbs please Andrew. Also happy to buy any components for the boards if you have surplus stock you want to get rid of.
#1043 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
I've no gripes at all, they are your boards, after all. I was just, perhaps a bit tongue -in-cheek, pointing out that it wasn't what I designed.IslandPink wrote: ↑Sun Feb 03, 2019 12:44 pm But seriously ( folks ) do you have a residual gripe about the GK-71 application ? - after all, it seemed to be merely a matter of feeding it with a 24V SMPS and making sure one or two caps on the board were 35V rated, as I remember ( and the heatsink up to scratch ) ?
Analogue, the lost world that lies between 0 and 1.
#1044 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
Max I have 6 spare (small) boards from Andrew which I plan to use shortly. I'm going to be putting in an order (either Farnell or RS) soon so let me know if you need components. We're unlikely to cross any significant price points but you never know - plus I have spares of some items.
Same applies if anyone else needs components for the boards.
EDIT - there are some savings to be had. For example the Panasonic caps are £1.78 <10, £1.05 between 10 and 24
#1045 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
Andrew - Farnell no longer stock the 470k CC TE 1/4W. They have the 1/2W equivalent in stock, but only 203 and not restocking I think. I'm going to be ordering at least 18 at 35.8p. Next price point is 50 at 25.6p
https://uk.farnell.com/neohm-te-connect ... ?st=Carbon
Similar with 1K - 1/4W awaiting delivery, 1/2W in stock
https://uk.farnell.com/neohm-te-connect ... dp/1265117
Any reason not to use the 1/2W versions ? Don't think it will be a problem room wise.
EDIT 2 - the big cost is the surface mount caps.
1+ = £4.87
50+ = £3.45
I need 12, I guess we're unlikely to get to 50 but let me know anyone who needs them.
EDIT 3 - Andrew I happen to have plenty of 1N4004 in stock, I assume no harm using those in place of the 1N4001 ?
https://uk.farnell.com/neohm-te-connect ... ?st=Carbon
Similar with 1K - 1/4W awaiting delivery, 1/2W in stock
https://uk.farnell.com/neohm-te-connect ... dp/1265117
Any reason not to use the 1/2W versions ? Don't think it will be a problem room wise.
EDIT 2 - the big cost is the surface mount caps.
1+ = £4.87
50+ = £3.45
I need 12, I guess we're unlikely to get to 50 but let me know anyone who needs them.
EDIT 3 - Andrew I happen to have plenty of 1N4004 in stock, I assume no harm using those in place of the 1N4001 ?
#1046 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
The 1N00x diodes should be fine, can't see why not?
The correct 470K CC resistors are available from RS, does that help? I suspect the 1/2 watt ones will be fine as well, if a little over-kill.
Yep, the caps cost a fortune, pity as I just bought 24 for a a mini buy.
Andrew
The correct 470K CC resistors are available from RS, does that help? I suspect the 1/2 watt ones will be fine as well, if a little over-kill.
Yep, the caps cost a fortune, pity as I just bought 24 for a a mini buy.
Andrew
Analogue, the lost world that lies between 0 and 1.
#1047 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
Thanks yes I was just looking at RS and doing a price comparison. I'm going to place orders tonight, so if anyone wants to jump on the bandwagon let me know SOON.Andrew wrote: ↑Tue Feb 12, 2019 4:11 pm The 1N00x diodes should be fine, can't see why not?
The correct 470K CC resistors are available from RS, does that help? I suspect the 1/2 watt ones will be fine as well, if a little over-kill.
Yep, the caps cost a fortune, pity as I just bought 24 for a a mini buy.
Andrew
The caps are half the price on RS, but need to be back ordered. EDIT - unable to be back ordered, Mouser and Digikey show them as 52 week lead time.
OK I'm going to order the 1/4W CC resistors from RS as they are in stock and cheaper even than bulk buying from Farnell. Everything else looks right from Farnell.
#1048 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
I’ve eight small boards coming from Andrew for my Pinnacle OTL build. In retrospect I should perhaps have requested large boards so I could use the chassis as heat sink.
Given I will be using the small boards, and there will be four mounted inside each monoblock chassis, I’m a little concerned that heat may be a problem, so to minimise this what’s the minimum input I could get away with to run a 300b?
Other possibilities could be drilling to bolt the top of the heat sinks directly to the chassis with some thermal paste, this would act as the fixing rather than some nylon pillars and presumably increase dissipation.
Or perhaps make up some boards for the amps to sit on with cut outs and pc cooling fans fitted.
Some advice from the panel would be much appreciated.
Given I will be using the small boards, and there will be four mounted inside each monoblock chassis, I’m a little concerned that heat may be a problem, so to minimise this what’s the minimum input I could get away with to run a 300b?
Other possibilities could be drilling to bolt the top of the heat sinks directly to the chassis with some thermal paste, this would act as the fixing rather than some nylon pillars and presumably increase dissipation.
Or perhaps make up some boards for the amps to sit on with cut outs and pc cooling fans fitted.
Some advice from the panel would be much appreciated.
#1049 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
I used the large boards and mounted the heatsinks on 2mm copper sheet (my chassis is wooden) at the back of the amp. I can't see how you would do that with the small boards. If you're concerned with heat then a small silent fan might be a good idea, along with suitable holes for airflow. Although I haven't wired them in yet, I have mounted 2 fans at the back of my cupboard and put a circuit together which uses thermistors in the amp to automatically control the fan speed. The fans themselves are very cheap and small.Ali Tait wrote: ↑Tue Feb 12, 2019 10:19 pm I’ve eight small boards coming from Andrew for my Pinnacle OTL build. In retrospect I should perhaps have requested large boards so I could use the chassis as heat sink.
Given I will be using the small boards, and there will be four mounted inside each monoblock chassis, I’m a little concerned that heat may be a problem, so to minimise this what’s the minimum input I could get away with to run a 300b?
Other possibilities could be drilling to bolt the top of the heat sinks directly to the chassis with some thermal paste, this would act as the fixing rather than some nylon pillars and presumably increase dissipation.
Or perhaps make up some boards for the amps to sit on with cut outs and pc cooling fans fitted.
Some advice from the panel would be much appreciated.
The board needs I think about 4v to regulate, so you'll need about 9v peak, or 6.3v RMS transformer. I use a 7v with my 45s, which are 2.5v 1.5A. 300Bs with a 6.3v transformer should dissipate MUCH less heat than my 45s and I haven't had a problem with 12 boards in the amp (4 45s, 4 26s, 4 71As). Yes they are mounted to vertical copper sheets, but still.
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#1050 Re: DHT Heater using VCCS - PCB or Kit (Possible Group buy)
I made some notes on heater tests for the 45. 5.62AC in was clean for 2.5V DC out.
http://www.audio-talk.co.uk/phpBB3/view ... 6&start=90
Another data point is that for GM70, with 23.8V DC in, 19.2V DC out is clean.
I think you can come down from 9V AC in, to about 8V AC or maybe slightly more. Transformer needs modelling with typical 245+AC unless you want to visit Andrew I or Dave
http://www.audio-talk.co.uk/phpBB3/view ... 6&start=90
Another data point is that for GM70, with 23.8V DC in, 19.2V DC out is clean.
I think you can come down from 9V AC in, to about 8V AC or maybe slightly more. Transformer needs modelling with typical 245+AC unless you want to visit Andrew I or Dave
"Once you find out ... the Circumstances ; then you can go out"