JoaMat
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Posts posted by JoaMat
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Happy Birthday!
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On 11/26/2022 at 1:02 AM, JoaMat said:
Some progress with Tube Hybrid(something).
PSU; left – Board with filament transformer and transformer for GRHV style regulator (+100V). To the right is Connex SMPS, put it in top of the first board and you have PSU with 6.3VAC, +100VDC and +/-30VDC.
Amplifier board with a tube daughter board. The required -5V is done on the amplifier board with a smd 7905 and a few capacitors.Will it work? Who knows?
The answer is No. It doesn’t work.
The bottom line is I’ve big trouble get it working. So, I'll put my version of a Tube Hybrid on hold. Probably for a looong time.
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On 12/12/2022 at 6:30 PM, Kerry said:
Here's my T2 supply (I've been meaning to post this for a while) - all the high voltages are Golden Reference supplies (even the -60V using a negative version of the GRHV79xxx). I've very pleased with how it performs
Thanks for posted picture Kerry. Your astonishing builds are very inspiring.
In the original T2 PSU the 60-volt section is regulated by LT783 which I think is good enough. But inspired by Kerry I did this little fellow (the small copper clad with test leads) to replace the LT783 regulator.
Connected to main board via three connections. Works like a charm – knock on wood.
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Thanks a lot for all your inputs, Kerry and simmconn.
Now it seems I’m back on track (knock on wood). Since “reflowing” the board and a new HN4A51J the PSU has been working for almost 24 hours with several on/offs. Voltage is stable, decreases some tenths of a volt from cold and than bang on the intended 150V.
After some struggling, I managed to measure the three faulty HN4A51J. All Q5:B are unknown components on the tester while Q5:A are PNP with hfe of 4 or 5?.
Now the angels are singing on my modified T2 with EML tubes.
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Thanks Kerry.
I just had to wait four hours for it break down this, the third, time. Same procedure as last time – replaced HN4A51J. Also reflowed all solder points – hot air – hope this will help...
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Here a schematics.
Four connections to main board. The raw DC is taken before the two 10m90s current limiters. Better would be after the limiters but no free hole for it.
Works like a charm I wrote. Yes, charming it is when it works. When it suddenly stops working and give 13V instead of 150V – that is more annoying than charming. It has happened two times so far since my last post. Not sure what’s wrong but I change Q5 (dual small PNP) with a new piece and then it works for couple of hours. Now I’m just waiting for the next breakdown.
Suggestions what might cause the problem are welcome!
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Almost a year has elapsed since I reduced the 300V section to 150V. The amplifier has worked well, and I haven’t noticed any sonically differences. So, some time ago I decided to make the same change on my modified T2 and its original T2 PSU we have at our summer cottage. But unfortunately, it was not possible to bring the voltage down to 150V. 190 – 200V was the lowest I got. I’ve had a Golden Reference power supply for the T2 in mind for a long time. Now I had to do something the get the desired 150V section with the original T2 PSU…
Made a daughter board with GRHV regulator for the original T2 PSU. Works like a charm.
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My impression is that this is intended to be a Muscle CFA3. You probably want 3U – at least.
No V12 engine in a Volkswagen Beetle.
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Some progress with Tube Hybrid(something).
PSU; left – Board with filament transformer and transformer for GRHV style regulator (+100V). To the right is Connex SMPS, put it in top of the first board and you have PSU with 6.3VAC, +100VDC and +/-30VDC.
Amplifier board with a tube daughter board. The required -5V is done on the amplifier board with a smd 7905 and a few capacitors.Will it work? Who knows?
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I guess those big things stand some heat. Why not just remove the throttle plate (vbe multiplier)... and feel the speed.
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Thanks. According datasheet they are to3p devices - a bit bigger than mjf1503x.
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The output transistors are 2sa1860 and 2sc4886 - right?
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Looks like transistor at heat sink are TO-220. Aren't the output transistors something bigger – TO-3P - so the board need a stretch?
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On 9/28/2022 at 2:51 PM, JoaMat said:
My CFA3smd something,
now powered from a switched mode power supply and equipped with a headphone protector. I’ll test this for a while and if I like it I might build a decent cage for it. Else I’ve a growing "good to have" closet.Now I’ve listened to CFA3smd something with switched mode power supply for almost 2 months and I’m happy with it.
So, no plan for a golden reference supply. I’m too lazy and I think the switched power supply is good enough for me.
Next “project” is how to power a Tube Hybrid. The Hybrid needs +100V, -5V and 6.3VAC for the tubes. The PSU has to be rebuilt. The amplifier board is finished, in theory…
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Maybe DN2535 (max voltage 350V) will work. Main difference to DN2540 (max voltage 400V) seems to be the maximum voltage. In stock at Mouser for roughly the same price as DN2540.
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Happy Birthday!
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Below is Tube Hybrid schematic. Why op amp U3?
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Some folks “over there” seem interested in Kevin’s Tube Hybrid. So, I removed a lot of small components from CFA3smd boards and replaced them with dual triode and double op amp. All according to info I found in Kevin’s library on google drive.
It should all fit in the same box as CFA3smd. PSU needs additional voltages, 5- and 100-volt sections and filament for tubes.
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On 9/23/2022 at 11:45 AM, BadgerMcBadger said:
is there any benefit for going higher than 400v? (for the carbon)
I'm satisfied with 400V. Started with 500V ten years ago. Reduced to 450V a couple of years ago and now 400V for all my electrostatics, including DIY T2.
16 hours ago, BadgerMcBadger said:is the BU2508AF a good replacement for the ksc5026m on the grhv?
You might try stn0214. It's surface mounted piece, but it can be soldered in standing on the ksc5026 pads.
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Happy Birthday!
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It’s a balanced board.
Inputs in center. Outputs at far right and far left. Positive rail at top edge and negative rail at bottom.
Dynahi boards mounted to 80 mm x 300 mm heat sinks. Here I’ve removed upper screws holding front and back plates to heat sinks and then “unfolded” for maintenance. To make it possible to unfold the wires are made “to long” when folded and then it looks like a snake nest. This is an Only DIY version, not to be sold...
I hope this makes it a bit clearer.
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Seems windows don’t like us. Try click and rightclick you around until you find a way.
Alternative go direct to the Gilmore source on Google Drive, click on first link and scroll down to you find protect3.zip.. Lots of good stuff here.
Sometimes it’s tricky to find the information you need, but it’s there – somewhere.
No V12 engine in a Volkswagen Beetle.
Merry Christmas!
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Merry Christmas!