With the resistor I got 32V. Reversed polarity and now I have 2V that changes downlwards slowly. Final capacitor is 33mF. Put a speaker on, no hum or something, complete silence, didn't measure with speaker on (forgot)
I tested 95V, we go to 50 C, I let it for 5 min.
I managed to burn my 1st FET. It happened during power off. I believe it is because the FET is still too hot and cooling shutdowns immediately. I must find a way to cut the cooling later than amplifier.
I will try from Monday again.
Where is zenmod to say its fugly?
I tested 95V, we go to 50 C, I let it for 5 min.
I managed to burn my 1st FET. It happened during power off. I believe it is because the FET is still too hot and cooling shutdowns immediately. I must find a way to cut the cooling later than amplifier.
I will try from Monday again.
Where is zenmod to say its fugly?
Duh, this is what happens when you are a n00b like me 
I have some questions...
- On PSU one of the two IRFPs are getting very hot, I have a minimal heatsink, is this correct? i need to put a big one?
- I have large capacitors 33mF in PSU. Is it better to use many smaller ones?
And some pics more..
I have some questions...
- On PSU one of the two IRFPs are getting very hot, I have a minimal heatsink, is this correct? i need to put a big one?
- I have large capacitors 33mF in PSU. Is it better to use many smaller ones?
And some pics more..
Attachments
Duh, this is what happens when you are a n00b like me
I have some questions...
- On PSU one of the two IRFPs are getting very hot, I have a minimal heatsink, is this correct? i need to put a big one?
- I have large capacitors 33mF in PSU. Is it better to use many smaller ones?
And some pics more..
first one (blue) is porn worthy
keep them coming
Today I am more excited... Tried the "full" power version, which on simulation gives 36Vp out on 4 Ohm with 2Vin, with Rsource 0.5 Ohms. 100V V from PSU.
Measured 3A on 193V, which was cool and fine.
Water cooling started working I touched one tube and was hot. Temp of FET 66 C with low speed of fans, 50 C with full speed.Is this a good temp?
Low speed is quiet enough, I can't hear them from 2-3 meters.
Voltage from ground to source of FET 2V. Rsource gets really hot, I put two 1 Ohm in parallel 15W each.
I let the system for one hour working. 0V on output terminals. I put a test speaker and I put my ear on the tweeter. Nothing. absolute silence.
I also burnt one FET, tested if it was what i was suspecting happened last time. If i turn power off, without the cooling working for some seconds more, the FET fries. I think I have to put some kind of delay there, or for now put two different switches.
Measured 3A on 193V, which was cool and fine.
Water cooling started working
I touched one tube and was hot. Temp of FET 66 C with low speed of fans, 50 C with full speed.Is this a good temp? Low speed is quiet enough, I can't hear them from 2-3 meters.
Voltage from ground to source of FET 2V. Rsource gets really hot, I put two 1 Ohm in parallel 15W each.
I let the system for one hour working. 0V on output terminals. I put a test speaker and I put my ear on the tweeter. Nothing. absolute silence.
I also burnt one FET, tested if it was what i was suspecting happened last time. If i turn power off, without the cooling working for some seconds more, the FET fries. I think I have to put some kind of delay there, or for now put two different switches.
I assume you are burning your output Mosfet? What is it? What is your schematic? I assumed you were using a bias supply but it seems that you are using a source resistor.
If you are running the Mosfet at 95V and 3A, or is it 4A since 2V across 0.5R source resistor, you are asking the Mosfet to dissipate 285W or 380W. This is probably way outside the SOA of the Mosfet.
If you are running the Mosfet at 95V and 3A, or is it 4A since 2V across 0.5R source resistor, you are asking the Mosfet to dissipate 285W or 380W. This is probably way outside the SOA of the Mosfet.
schematic in post #97.
@pinholer. I am pretty sure it is because the FET is too hot and suddenly pump stops cooling and obviously the effect you are referring makes things worse. There is no heatsink to take away the remaining heat. If I leave the cooling system for some seconds there is no issue. Tomorrow I ll add a second switch so I can keep the cooling on even if the main power is off. I have also ordered delay circuits, which I am going to use for PSU and in amplifier too.
I don't have a bias circuit, only a source resistor, 0.5 Ohm. The 2V are at edges of this resistor. So it should consume V*V/R or 8W. I had one of 15W but it was getting very hot, so I put two 15W in parallel, it is much better now.
Ben you are right, if 2V then Id is 4A. I am not very sure about accuracy of my multimeter, since the "good" one was measuring temperature. On analysis with LTSpice I remember Id was 5 Ap.
I also added fans on heatsink of FETs of PSU (IRFP 250), maybe I will put one pair more, now it has a pair, one for positive and one for negative. I have some small heatsinks for now, I have ordered bigger and maybe in the end pout them on the chassis, now are on the air. With fans working, I could touch for some seconds the heatsink.
I have put 120mF total for now, it will go to 200 mF approx when my coils arrive.
I know about the 300W+ that's why I am using the liquid cooler, which to be honest seems to do a great job. I let the system more than an hour running and seems very stable. Ambient temp was 29 C and when I have fans in full speed FET goes to 44 C in the end. I hope when it is working speakers consume some of this
I am also thinking to change the FET to IXTH16N50D2 which is a 16A device, the one I am using is a 6A.
I have also ordered big EXICONs and 2SK182ES whixh are on the wayto test them too (of course with different bias)
@pinholer. I am pretty sure it is because the FET is too hot and suddenly pump stops cooling and obviously the effect you are referring makes things worse. There is no heatsink to take away the remaining heat. If I leave the cooling system for some seconds there is no issue. Tomorrow I ll add a second switch so I can keep the cooling on even if the main power is off. I have also ordered delay circuits, which I am going to use for PSU and in amplifier too.
I don't have a bias circuit, only a source resistor, 0.5 Ohm. The 2V are at edges of this resistor. So it should consume V*V/R or 8W. I had one of 15W but it was getting very hot, so I put two 15W in parallel, it is much better now.
Ben you are right, if 2V then Id is 4A. I am not very sure about accuracy of my multimeter, since the "good" one was measuring temperature. On analysis with LTSpice I remember Id was 5 Ap.
I also added fans on heatsink of FETs of PSU (IRFP 250), maybe I will put one pair more, now it has a pair, one for positive and one for negative. I have some small heatsinks for now, I have ordered bigger and maybe in the end pout them on the chassis, now are on the air. With fans working, I could touch for some seconds the heatsink.
I have put 120mF total for now, it will go to 200 mF approx when my coils arrive.
I know about the 300W+ that's why I am using the liquid cooler, which to be honest seems to do a great job. I let the system more than an hour running and seems very stable. Ambient temp was 29 C and when I have fans in full speed FET goes to 44 C in the end. I hope when it is working speakers consume some of this
I am also thinking to change the FET to IXTH16N50D2 which is a 16A device, the one I am using is a 6A.
I have also ordered big EXICONs and 2SK182ES whixh are on the wayto test them too (of course with different bias)
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Go ask in the MoFo thread in this section. Choke-loaded MOSFET followers can have a large inductive kick if power is disconnected suddenly. A Zener G-S is better, but maybe not proof against all events.
I may be missing a joke. The inductor will kick-up above the supply rail for potentially double the output voltage. A light bulb (resistor) won't.
Joke: Zen Mod said that the picture was too dark, so Pinholer said replace the choke with a light bulb. 
Looking at the schematic in post #97, it is very low resolution. I can see that you are floating a bipolar supply. Is that to limit the transformer and capacitor voltages instead of using a single V supply with higher transformer and capacitor voltages?
Your simulation took 9489 seconds (2.63 hours) to run. I would think that there is something wrong with your model.
You said your PS devices are IRFP250. What is your amplifier output device? Also it is not clear which device burned up. Was it the output device or the PS device?
Looking at the schematic in post #97, it is very low resolution. I can see that you are floating a bipolar supply. Is that to limit the transformer and capacitor voltages instead of using a single V supply with higher transformer and capacitor voltages?
Your simulation took 9489 seconds (2.63 hours) to run. I would think that there is something wrong with your model.
You said your PS devices are IRFP250. What is your amplifier output device? Also it is not clear which device burned up. Was it the output device or the PS device?
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