A good use of your BiBs. Over the weekend stumbled upon a record store. Pleased to see "Back in Black" was one of Rolling Stone's top 100 albums of all time. Brought me right back to 1980, a friend had a little Ford Fiesta with a big Bose cassette system, played that constantly.
@NeoTheOne there are two of those, each is a 5Vdc power supply which power the JLSounds I2S over USB board, which per what I've read here is an improvement over powering that board from the USB port. Both of those small power supplies also come from JLS. Conveniently, there are jumpers that allow precisely optimized voltage for each side of the I2S over USB.
@JKiriakis what drill bit and tap do you use for drilling and tapping hole in the heat sink for to-220 Mosfets? What size nut and bolt to use ? I'm not able to nail down the right size on amazon.
@NeoTheOne I opted to through bolt the MOSFETs with M3 hardware. To do that required careful measuring of the distance between the center pin vias on the PCB which equate to the FET mount hole and the gaps between the fins of the heat sinks. Distance between FETs fortunately land between the fins. I studied the CAD drawings of the sinks closely before ordering. And essentially guessed on size and dissipation based on observations of other members builds on the thread and Salas’ original write up. Big enough on my 30V BiB and larger than necessary on the 5V in my case with modest current requirements.
Recommend use of a drill guide whether you drill and tap or through bolt, I had issues with insulating the FET bodies from the sinks.
Recommend use of a drill guide whether you drill and tap or through bolt, I had issues with insulating the FET bodies from the sinks.
I replaced the resistor Rf and now the power supply is working but the output is 2.6VDC even if i adjust the pot. The input VAC=15Vrms
M1 runs hot but M2 is running cold though.
M1 runs hot but M2 is running cold though.
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With what R1 value (2Ω?) and with what dummy load resistor value you test right now? To see if there is enough CCS current produced for this test first of all. Also, is there near 0.6V DC voltage across the R1 legs?
The CCS apparently works at 289mA (0.578V/2Ω). To reach 12V Vout on a 10Ω dummy load, takes 1200mA.
Pictured reading 2.628V/10Ω=262.8mA i.e. very near to the CCS calc. There can also be tolerances in R1 etc.
This dummy load overpowers the CCS and it naturally limits the output voltage to CCS ability with given load.
Use a 100Ω no less than 2W power dummy load resistor to see if your original 12V Vout goal can be reached.
If it can, see if it can also serve your real load. In case of current limiting and voltage loss again, use 1.5Ω R1.
About your small sinks, you read earlier contributors posts. For now don't let it idle for long not to get too hot.
Pictured reading 2.628V/10Ω=262.8mA i.e. very near to the CCS calc. There can also be tolerances in R1 etc.
This dummy load overpowers the CCS and it naturally limits the output voltage to CCS ability with given load.
Use a 100Ω no less than 2W power dummy load resistor to see if your original 12V Vout goal can be reached.
If it can, see if it can also serve your real load. In case of current limiting and voltage loss again, use 1.5Ω R1.
About your small sinks, you read earlier contributors posts. For now don't let it idle for long not to get too hot.