• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

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jcalvarez

Member
Paid Member
2021-04-16 4:57 pm
Dunfermline, UK
I made a little bench for prototyping. Nothing special, but I like it :)
Voltages (all DC)
B+ up to 560V, 200mA
12V 13A (powers the B+ inverter and 6.3V regulator.)
6.3V 2.5A max.
Big silent fan to be able to drive the B+ inverter at 100W

IMG_20220411_110151.jpg

IMG_20220411_110012.jpg
IMG_20220411_110332.jpg
IMG_20220411_110950.jpg
 
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jcalvarez

Member
Paid Member
2021-04-16 4:57 pm
Dunfermline, UK
You won't need the fan. It looks like you got the parts off of my shelf!
That 12V 13A supply is excellent. I routinely draw 5A from one in a 70°C enclosure - no ventilation. No failures in the years I've used them yet, not even the cheap filter caps.
I know, but driving the B+ converter hard takes 8 amps, plus some heater power and you will be in the 10A region. I had the fan anyway.
I ran the thing loaded at 100W on B+ today, and without the fan you can fry eggs on the 12V rectifier heatsink, and the B+ converter drivers get very hot. Peace of mind 😀
P. S Yes, I stole your ideas 😁
 
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kodabmx

Member
Paid Member
2011-10-31 1:00 am
Toronto
Ah. Didn't realize you were running it that hard :) I like the fact it will start into a load like cold heaters instead of crying like a baby lol
The double fuse is a nice touch - there's already a fuse on the DC2416 :)
Which MOSFETs is it using? If/when they blow, you can replace then with better ones :)
The older ones I had used 3205 (but generic, not IRF) but the newer ones are using some CS80N80A...
How hot was the coil on the boost converter? I've had at least one get much hotter than the heatsinks.
 
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jcalvarez

Member
Paid Member
2021-04-16 4:57 pm
Dunfermline, UK
Ah. Didn't realize you were running it that hard :) I like the fact it will start into a load like cold heaters instead of crying like a baby lol
The double fuse is a nice touch - there's already a fuse on the DC2416 :)
Which MOSFETs is it using? If/when they blow, you can replace then with better ones :)
The older ones I had used 3205 (but generic, not IRF) but the newer ones are using some CS80N80A...
How hot was the coil on the boost converter? I've had at least one get much hotter than the heatsinks.
The inverter uses YPI7575c. I will buy some more inverters, now that I see that it works properly. I would replace the heatsinks with taller ones, it comes with 25x15x10. The transformer seemed fine, I could hold a finger on it.
On the 12V SMPS, the rectifier diodes could probably be replaced with lower dropout voltage ones, because it's heatsink is the one that get's really hot without a fan.
 

jcalvarez

Member
Paid Member
2021-04-16 4:57 pm
Dunfermline, UK
Nice. Which module is the inverter providing up to 560V @ 200mA?
The inverter is from Aliexpress, bought it after noticing that @kodabmx used it in one of his amps:
https://www.aliexpress.com/item/326...-1;8.55;-1;[email protected];GBP;search-mainSearch

Looks like this:
100-280V_Inverter.png


I can only vouch that this one works. I previously ordered a slightly different one, had silver heatsinks and no rectified output, and it died after 15 min of being lightly loaded. This one works quite well, gives a square rectified or AC outputs, 110/200/220/280, I used it with a doubler, just two 22uf caps connected to the output and the middle to one of the AC taps.

I measured again to be sure, and is around 525V @220mA, 560V @90mA.
As is the case with many boards from Aliexpress, your mileage may vary. I have tested the combination for around 3 hours, loaded at 220mA, so far so good. Difficult to get a better value for £8.55 inc delivery. I paid ~£130 for a Hammond 372JX a while ago. The whole setup here, including the 12V 150W SMPS is less than £20.
 
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kodabmx

Member
Paid Member
2011-10-31 1:00 am
Toronto
You might get less sag with bigger doubling caps... 47µF or 100µF but the coil will run hotter. I usually use the AC output and my own HER208 diodes BTW... Not sure it makes any difference.

Meanwhile, here's a shot of "When the socket needs to be replaced but you want to listen to music NOW!" :)
 

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NickKUK

Member
2019-12-28 9:16 pm
The inverter is from Aliexpress, bought it after noticing that @kodabmx used it in one of his amps:
https://www.aliexpress.com/item/32688618917.html?spm=a2g0o.productlist.0.0.1d364a12fPnUpq&algo_pvid=ebf3e158-aea8-4bce-94a8-40a4366f7f54&algo_exp_id=ebf3e158-aea8-4bce-94a8-40a4366f7f54-0&pdp_ext_f={"sku_id":"60468402583"}&pdp_pi=-1;8.55;-1;[email protected];GBP;search-mainSearch

Looks like this:
View attachment 1043696

I can only vouch that this one works. I previously ordered a slightly different one, had silver heatsinks and no rectified output, and it died after 15 min of being lightly loaded. This one works quite well, gives a square rectified or AC outputs, 110/200/220/280, I used it with a doubler, just two 22uf caps connected to the output and the middle to one of the AC taps.

I measured again to be sure, and is around 525V @220mA, 560V @90mA.
As is the case with many boards from Aliexpress, your mileage may vary. I have tested the combination for around 3 hours, loaded at 220mA, so far so good. Difficult to get a better value for £8.55 inc delivery. I paid ~£130 for a Hammond 372JX a while ago. The whole setup here, including the 12V 150W SMPS is less than £20.

I might get myself a couple of these for bench testing given their flexibility.
F21C23A3-F88C-454D-985A-565141ACB1E0.jpeg

4D459E3B-D8F0-4EF6-8B0C-75232A52F7DF.jpeg

Current project - late 1950s phillips receiver + record deck.
 
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