No problem 🙂
Let me know how it works out. There are some jumpers (not marked on the silkscreen) that you'll need to pay attention to and one in particular that goes from the 'centre tap' of the transformers to the star ground. This is on the silkscreen layer of the pdf and since I do the silkscreen in copper, it comes out in the etch. You can use a wire to link these two areas.
I may find time later today to etch the board but may not have time to stuff it.
Let me know how it works out. There are some jumpers (not marked on the silkscreen) that you'll need to pay attention to and one in particular that goes from the 'centre tap' of the transformers to the star ground. This is on the silkscreen layer of the pdf and since I do the silkscreen in copper, it comes out in the etch. You can use a wire to link these two areas.
I may find time later today to etch the board but may not have time to stuff it.
There are 5 - 2 at the star ground (to pick the best point for the cap multiplier), 2 near terminal block P2, one near Q4.
MJL 21193
Your power supply seems to be an excellent fit to supply to the front end of Goldmund clone instead of the original.
However, I have a question: On the input capacitors can I have +/-90V DC. The maximum voltage out I get is +/-78.4 VDC.
If possible, how can I obtain further +/-1.5 V,so that I achieve the desired
+ / -80 V DC (=reduce voltage drop in the "circle" MPSA 42/92, MJE 15030/31 and LM 317/337)??
Eivind Stillingen
Your power supply seems to be an excellent fit to supply to the front end of Goldmund clone instead of the original.
However, I have a question: On the input capacitors can I have +/-90V DC. The maximum voltage out I get is +/-78.4 VDC.
If possible, how can I obtain further +/-1.5 V,so that I achieve the desired
+ / -80 V DC (=reduce voltage drop in the "circle" MPSA 42/92, MJE 15030/31 and LM 317/337)??
Eivind Stillingen
You made the board? It worked?
10 volts is not much margin for this regulator, but it may be doable. I'm surprised you have that much output actually.
Referring to the layout, R4 and R2 (R10 and R12 on the negative side) form a voltage divider and you need to adjust these values to increase the voltage at the base of Q1 (Q3 neg). Changing R2 and R12 to ~1k will increase the voltage before the LM's (needs to be at least 83VDC before the regs).
The trimpots (VR1, VR2) on the adjust pins should give enough variability to get the voltage correct.
10 volts is not much margin for this regulator, but it may be doable. I'm surprised you have that much output actually.
Referring to the layout, R4 and R2 (R10 and R12 on the negative side) form a voltage divider and you need to adjust these values to increase the voltage at the base of Q1 (Q3 neg). Changing R2 and R12 to ~1k will increase the voltage before the LM's (needs to be at least 83VDC before the regs).
The trimpots (VR1, VR2) on the adjust pins should give enough variability to get the voltage correct.
MJL 21193.
Your board works just fine.
I changed R2 from 2,2 Kohm to 1,5 Kohm, and voila I got my +/- 80 V DC!!
Eivind Stillingen.
Your board works just fine.
I changed R2 from 2,2 Kohm to 1,5 Kohm, and voila I got my +/- 80 V DC!!
Eivind Stillingen.
It may be interesting to add an rcr at the output end of the regulated power supply, from v+ to v-, not connected to the 0v line.
The front end supply? It should be able to supply up to 1A (bottleneck is the LM's), but that would be a bit counterproductive. It wasn't designed as a high current regulator.
The main supply (if it works 😀) could probably do 10A or more, depending on how many pass transistors it has.
Heyya Dan, long time! Keeping out of trouble?
Oh, no, not really. 🙂
I've got 6 concurrent projects running right now, so its a bit busy and kinda spendy. I also made a huge mistake with a "web accelerator" that attempted to download the earth, which was actually kind of slow. And, for the first time, last week, I didn't lose a fight with a vacuum tube harmonic filter.
Question: Does your higher voltage toroid still growl when its clamped into its rubberized mount, or does that just happen to squeeze down the loose turn of wire so that its quiet?
Yeah, I completely understand this - especially the spendy part.🙂
If your transformer is making a growling noise, it may be excess DC on the mains. If it is just making a buzzing sound, it is loose internal winding and not much can be done to fix it. I had one transformer that I submerged in urethane overnight and let dry - this made it a bit more quiet but it didn't completely solve the problem.
Submerging in varnish/urethane/similar will not get the viscous liquid into all the air spaces in between the windings and in between loose laminations. It will have a hard time just getting past the outer insulation layers and then there is the inner insulation layer between secondary and primary.
There are two solutions.
The best is double vac/vac. Submerge the transformer in your bath of sealer. Apply a vacuum to expand the air out through the insulations etc. and then release the vacuum to let the sealer be forced back in by atmospheric pressure to the re-compressed air. Repeat the vacuum and release process a second time.
Next best is to heat the sealer bath with the transformer submerged. The heated air expands and forces itself out. Cool the bath and transformer and the remaining air such that the cooled air sucks the sealer into the transformer. Again heating for a second cycle improves the penetration. You need a "slow" sealer for both methods, particularly for the heated version.
These two methods make a fairly good attempt at replacing the air inside the transformer with sealer.
Now let it all dry out/set. A drying/setting that does not require evaporation (i.e. the sealer sets) will be much better than a sealer that dries by evaporating the solvent. The evaporating solvent ends up to some extent inside the transformer creating gas bubbles in the setting varnish.
There are two solutions.
The best is double vac/vac. Submerge the transformer in your bath of sealer. Apply a vacuum to expand the air out through the insulations etc. and then release the vacuum to let the sealer be forced back in by atmospheric pressure to the re-compressed air. Repeat the vacuum and release process a second time.
Next best is to heat the sealer bath with the transformer submerged. The heated air expands and forces itself out. Cool the bath and transformer and the remaining air such that the cooled air sucks the sealer into the transformer. Again heating for a second cycle improves the penetration. You need a "slow" sealer for both methods, particularly for the heated version.
These two methods make a fairly good attempt at replacing the air inside the transformer with sealer.
Now let it all dry out/set. A drying/setting that does not require evaporation (i.e. the sealer sets) will be much better than a sealer that dries by evaporating the solvent. The evaporating solvent ends up to some extent inside the transformer creating gas bubbles in the setting varnish.
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A smidge too much work for me Andrew. The one I tried to silence was from a car battery charger - EI core with no coating at all. I use it to power a Pioneer car CD/radio for my back deck. The slight buzz is not detectable when the musik is playing.
The last good toroid that had a buzzing problem, I used in my lab power supply. Still a bother but tolerable.
The last good toroid that had a buzzing problem, I used in my lab power supply. Still a bother but tolerable.
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The better ones I have are dead silent. These were salvaged from some fairly decent receivers and amps. The one pictured earlier in this thread is from an early 80's Realistic receiver and worth a lot more than the $10.00 I paid for it at Goodwill.
The toroid that I used in my lab supply is a Plitron, but it is not potted. Funny, as I had read somewhere that all Plitron's are potted.
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I'm now leaning towards planning for external psu's for my future amp projects. Put the heavy noisy radiating trafo's and rectifiers in a steel box out of sight, built a nice amp in a nice box in plain sight. Easier to upgrade the two things separately too.
It's a good idea, one I used before but it has drawbacks. I found the biggest difficultly in finding a suitable 3 conductor connector to run the power from the supply to the amp. Ideally, it needs to be different than the typical IEC connector or run the isk of someone sending in raw mains voltage.
Building 2 boxes instead of one, even if one is less cosmetically pleasing than the other.
Building 2 boxes instead of one, even if one is less cosmetically pleasing than the other.
Thanks man!!
It seems like this might work?
One very clean shop vac
One heavy duty "freezer" ziplock bag
One bottle off brand acrylic floor wax
One noisy transformer
Method: Put transformer into bag inside the cleaned shop vac and fill the bag up with $1 acrylic. Put the lid on the shop vac, switch it on and block the hose for a few seconds, switch it off, repeat a couple of times. Set the transformer on wax paper. Pour the acrylic floor wax back into the bottle. Set the now very shiny transformer in the sun for a day.
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