Not to nit-pic, but would you please label the secondary coils? As drawn I'm thinking the primary side of the trannie is 2 x 24 volts.
I could be all wet, but if the secondaries are 2 x 24 volts, you should be getting more than 15 volts out with a CRC arrangement. Conservatively: 1.2 times 24 = 28.8 volts. Are you planning to drop ~ 14 volts across the CRC resistor?
edit: Oh, I see Nixie caught this point already...
If the primaries are run in series, you can half the secondary out, but you cut the V/A of the trannie in half as well.
Another thing: I'd use two rectifiers per trannie and couple the dc, not the ac.
I could be all wet, but if the secondaries are 2 x 24 volts, you should be getting more than 15 volts out with a CRC arrangement. Conservatively: 1.2 times 24 = 28.8 volts. Are you planning to drop ~ 14 volts across the CRC resistor?
edit: Oh, I see Nixie caught this point already...
If the primaries are run in series, you can half the secondary out, but you cut the V/A of the trannie in half as well.
Another thing: I'd use two rectifiers per trannie and couple the dc, not the ac.
1.2 is waaay too conservative. In simulation his arrangement is giving me over 30 V after the filters. The reason is he has very large capacitance (I'd say too large, you're just wasting space; 36mF x 3 in a CRCRC per rail would give nearly as good result with half the total capacitance).carpenter said:
Hi Nixie,
I'm thinking of the PS under load. I'm running a 25v transformer in a CLC arrangement and getting slightly over 30 volts in my ZV7-T.
Sorry for not making that point clear.🙂
I'm thinking of the PS under load. I'm running a 25v transformer in a CLC arrangement and getting slightly over 30 volts in my ZV7-T.
Sorry for not making that point clear.🙂
power supply
Im shooting for +-15 V rail. The reason I had so much capacitence is that I read that you should use as much as you can afford. If you are using
PSUD are you using a current source -sink load?
with 24 volt rms by calculation I get 32 v dc
Im shooting for +-15 V rail. The reason I had so much capacitence is that I read that you should use as much as you can afford. If you are using
PSUD are you using a current source -sink load?
with 24 volt rms by calculation I get 32 v dc
Try designing a ful wave rectifier, rather than a full wave bridge.
edit: that's going to come out too low. 10.8 volts. Darn.
edit: that's going to come out too low. 10.8 volts. Darn.
What are you talking about carpenter? The simulation I mentioned is under load. Drop in the windings is taken care of by adding impedance to the transformer.3
As for full wave vs bridge, that doubles the resistive losses in the windings, since they are used half as often at twice the current.
tenderland, for +/-15 V and drawing 6.7 A from the supply, that only makes sense on 4 ohm speakers. Was this your intention?
24 V RMS transformers are way too much for 15 VDC, even with choke-input filter. 13 V would have been sufficient.
As for full wave vs bridge, that doubles the resistive losses in the windings, since they are used half as often at twice the current.
tenderland, for +/-15 V and drawing 6.7 A from the supply, that only makes sense on 4 ohm speakers. Was this your intention?
24 V RMS transformers are way too much for 15 VDC, even with choke-input filter. 13 V would have been sufficient.
load
What value are you using for the load?
No Nixie I just was having a difficult time finding a good suitable transformer and that is one I found at Plitron ? My intention was +- 15v
rail 8 ohms.
What value are you using for the load?
No Nixie I just was having a difficult time finding a good suitable transformer and that is one I found at Plitron ? My intention was +- 15v
rail 8 ohms.
Nixie, I'm speaking from an actual working model, not a simulator--my amplifier.
According to my text, a full wave rectifier has the same full wave signal out as a bridge rectifier, but at 1/3 the voltage.
I'm just making suggestions.🙂
According to my text, a full wave rectifier has the same full wave signal out as a bridge rectifier, but at 1/3 the voltage.
I'm just making suggestions.🙂
Frankly I think Plitron sucks. It's overpriced. Why not try custom transformer maker. Some won't charge really more than Plitron for a custom one. Try Victoria Magnetics or see if there's something in your locale. Or go on eBay. Don't be afraid to get EI transformer if that's what's available. You really are only saving on size and nothing else by getting a toroidal one.
carpenter, my simulation is done in the exact same way as I did for my own supply, and when I built the supply, it matched the simulation. That is plenty of validation.
Ei
I have read a couple good articles making a case for IE tranys.
I will have to do a "reset" and see If I cant come up with a more practical design.
What value did you use for the load Nixie
I have read a couple good articles making a case for IE tranys.
I will have to do a "reset" and see If I cant come up with a more practical design.
What value did you use for the load Nixie
Whatever the total bias is. I assume you have figured that out from the Aleph-X spreadsheet. Monoblocks or stereo amp?
tenderland, I'm drawing my ideas from a text written by "Malvino". It suggests that your transformer would deliver 15.4457 volts out of the full wave rectifier. But, that's before filtering. With filtering it's closer to the peak ripple of 24 volts.
Sorry for the prior suggestion, I forgot to add the voltage of two secondaries together.🙂
Sorry for the prior suggestion, I forgot to add the voltage of two secondaries together.🙂
Whoa! Whoa!
Put on the brakes, guys.
One--I've had a fair amount of experience with Plitron. They make good transformers. Just snagged a few more the other day, in fact.
Two--The revised schematic looks okay to me, with the caveat that I'm short on time.
Three--24V secondaries are a bit rich if you're seeking 15V rails...but who said you have to use 15V rails? Certainly not me. I set the original Aleph-X rails to 15V just to make it easier for folks to find hardware...not to be a straightjacket. Got higher rails? Peachy! You'll have higher power and lower distortion. The caveat being that you'll need more VA on the transformer, more heatsinking, and a few more devices. But, hey, we're DIY, we laugh at heatsinks that weigh less than a young hippo. What? You say it's only the size of a trashcan? Harrumph! Go fetch a bigger one!
Four--If you were to go for an inductor at the beginning of the filter, you can bring in the voltage below the AC rating of the secondary--something along the lines of 20-22V should be doable.
Five--I'm not clear...have these transformers already been bought, or is this all on paper?
Six--I dunno...I'm way into sleep deprivation and my mind's fried. I'm not even sure I had a six. Somebody will have to make up a six for me...
Grey
Put on the brakes, guys.
One--I've had a fair amount of experience with Plitron. They make good transformers. Just snagged a few more the other day, in fact.
Two--The revised schematic looks okay to me, with the caveat that I'm short on time.
Three--24V secondaries are a bit rich if you're seeking 15V rails...but who said you have to use 15V rails? Certainly not me. I set the original Aleph-X rails to 15V just to make it easier for folks to find hardware...not to be a straightjacket. Got higher rails? Peachy! You'll have higher power and lower distortion. The caveat being that you'll need more VA on the transformer, more heatsinking, and a few more devices. But, hey, we're DIY, we laugh at heatsinks that weigh less than a young hippo. What? You say it's only the size of a trashcan? Harrumph! Go fetch a bigger one!
Four--If you were to go for an inductor at the beginning of the filter, you can bring in the voltage below the AC rating of the secondary--something along the lines of 20-22V should be doable.
Five--I'm not clear...have these transformers already been bought, or is this all on paper?
Six--I dunno...I'm way into sleep deprivation and my mind's fried. I'm not even sure I had a six. Somebody will have to make up a six for me...
Grey
I'm going to post my supply here. However, I intend to replace CRC with CLC for a bit higher voltage (there's also Mr Evil's capacitance multiplier after the CRC for virtually zero ripple). I still need to find proper inductors.
I'm using a switch to have multiple selectable voltages and bias currents (voltage by changing primary taps). Max 7 amps at 22 V.
What do people think about the occasionally seen capacitors across rails rather than rail to ground? I think I've seen bipolar supplies in that configuration in the tubecad journal.
I'm using a switch to have multiple selectable voltages and bias currents (voltage by changing primary taps). Max 7 amps at 22 V.
What do people think about the occasionally seen capacitors across rails rather than rail to ground? I think I've seen bipolar supplies in that configuration in the tubecad journal.
Grey's post got me to thinking--always a good thing.
I always use a CLC and sometimes CLCLC filter for my amps. I've even utilized the LCLC combination to drop voltage. This may explain why I draw more conservative conclusions regarding voltage calculations.
This is my round about way of saying that Nixie's thoughts are perfectly valid.
I'm sorry if I seemed argumentative.
I always use a CLC and sometimes CLCLC filter for my amps. I've even utilized the LCLC combination to drop voltage. This may explain why I draw more conservative conclusions regarding voltage calculations.
This is my round about way of saying that Nixie's thoughts are perfectly valid.
I'm sorry if I seemed argumentative.
My Aleph-X Monoblocks were built using Plitron 300VA trafos with dual 12V secondaries. With a bridge rectifier and CLC supply filter I got rails of exactly +/- 15V, with each amp drawing a 5A bias current (My amps produce 50W output into both 8 and 4 ohms). From my experience, the 300VA trafo's are OK but I am considering replacing them with 500VA trafos as they occasionally have a slight audible hum whe the amps are on. I am certain that the 300VA trafos are operating within their rating, but the hum is a bit of a detraction from their appeal.
I should also mention that I too like the Plitrons, but I've also had good success with both Hammond and Amveco transformers as well.
My two cents worth of experience ..... I hope it helps.
Cheers, Terry
I should also mention that I too like the Plitrons, but I've also had good success with both Hammond and Amveco transformers as well.
My two cents worth of experience ..... I hope it helps.
Cheers, Terry