rCRCRC will overcome the excess voltage (provided Merlin designs for it) and the resistors will dissipate the heat.
I have used my main power amp PSU with +43Vdc to power a jFET crossover that uses/needs only +28Vdc .
It has a RCRC using six 600mW resistors and they don't get hot, just pretty warm.
Oh, and a bypassing Zener as a bit of extra protection in the event of overvoltage.
I have used my main power amp PSU with +43Vdc to power a jFET crossover that uses/needs only +28Vdc .
It has a RCRC using six 600mW resistors and they don't get hot, just pretty warm.
Oh, and a bypassing Zener as a bit of extra protection in the event of overvoltage.
You can but you will have 57VDC before the shunts so these will have to dissipate a little bit more (around 3.3W) .... just be sure you use extra big sinks (like 4deg/W).
Salas,
I'm having problems with the regs, at first I could only get 20v, then they dropped to 5.5. The preamp circuit is not connected (rail resistors pulled). Input voltage 45v. At first R1 was smoking, so replaced it with 5W to troubleshoot. Had to replace Q2 with a K170 and changed R6 to 33 ohm. I get no adjustment from VR2? With the regulator running correctly what is the base and collector voltage on Q4? Both regs have the same problem so I have nothing to go by??? I may have a counterfeit lot of K117? Can this be built with K170? Or I will have to order some K117 from Tea Bag (haven't had luck with eBay parts).
I'm having problems with the regs, at first I could only get 20v, then they dropped to 5.5. The preamp circuit is not connected (rail resistors pulled). Input voltage 45v. At first R1 was smoking, so replaced it with 5W to troubleshoot. Had to replace Q2 with a K170 and changed R6 to 33 ohm. I get no adjustment from VR2? With the regulator running correctly what is the base and collector voltage on Q4? Both regs have the same problem so I have nothing to go by??? I may have a counterfeit lot of K117? Can this be built with K170? Or I will have to order some K117 from Tea Bag (haven't had luck with eBay parts).
Bad or wrong semis then. Either fakes or wrong idss or dead Mosfets. When not having a load the output Mosfet could over heat btw. K170 can be used for meantime (with proper Vref resistor regarding IDSS). Check that the BC transistors are the right ones in the right place at the regs too.
Meaning Q4x? Got to have Vout -VGS(Q6x) across in normally working situation. 2SK117GR fakes could fail in Q2x position (sabotaging the main CCS) and not provide enough IDSS under 0.6V VBE (Q3x) to drive the resistive Vref (VR2x R3x) high enough when with the recommended resistors values. Better fakes can work but unstably or with higher white noise. K170 could be driftier but it should fix the gross problems. Marginal Q2x VDS max at 45VDCin though.
Better late than never!
My FSP proved the best project yet for my Michel Gyro / Morch UP-4 / VDH Frog rig!
Everything worked perfectly from the start and adjustment was as easy as it gets thanks to Salas detailed instructions.
As expected, sound was very good and now I feel as a proud owner of a rare diy device...
My FSP proved the best project yet for my Michel Gyro / Morch UP-4 / VDH Frog rig!
Everything worked perfectly from the start and adjustment was as easy as it gets thanks to Salas detailed instructions.
As expected, sound was very good and now I feel as a proud owner of a rare diy device...
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Very very nice setup... I agree, the best so far regarding phono amplification.
Regards
