PSU Connections
Thanks pchw, that sounds encouraging - now I need to find place on in he cd player! Could I use smaller caps that 10000uf 50v?
Thanks pchw, that sounds encouraging - now I need to find place on in he cd player! Could I use smaller caps that 10000uf 50v?
Here is the schematic.
It is also included in PA's enhanced schematic.
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That's the version that has the lower rectifier bridge drawn reversed.
The snubber is in the wrong place.
It should be before the rectifier.
The 0u1F may cause ringing rather than removing it.
The snubber is in the wrong location.
The ringing when a step change happens is between the inductance of the transformer winding and the rectifier diode when it switches off leaving the diode capacitance to ring in that LC combination. It's that LC ringing that requires damping. That is where the snubber should be.
The ringing when a step change happens is between the inductance of the transformer winding and the rectifier diode when it switches off leaving the diode capacitance to ring in that LC combination. It's that LC ringing that requires damping. That is where the snubber should be.
Thanks for the direction AndrewT, now I am tempted to put my SR project aside and build a Quasimodo. It will also redirect me to pulling out my oscilloscopes and dusting them off. For now, I will have to figure a way of relocating the filter components - there are some excellent diagrams in the Quasimodo thread that illustrates filter locations before rectifiers. I am considering moving the offending parts to the appropriate location to under the pcb.
Next objective is finding a Quasimodo board V4!
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For now I will concentrate on using the existing components. Will keep you posted.
Next objective is finding a Quasimodo board V4!
.For now I will concentrate on using the existing components. Will keep you posted.
If you've already got a signal generator and two channel oscilloscope, you can use the "ExtraLight" test procedure without building a Quasomodo (or CheapoModo) printed circuit board. It's described in post #561 here. The basic idea is shown in the figure below.
Series resistor R1 works with the square wave generator to inject a current step into the transformer secondary + snubber. This very large dI/dt stimulates the RLC resonant circuit into oscillatory ringing, which you can damp by twirling the knob of 20-turn trimmer potentiometer Rs. The whole arrangement uses test equipment you already have on your bench, today, without requiring you to fab a new PCB or source any new components.
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Series resistor R1 works with the square wave generator to inject a current step into the transformer secondary + snubber. This very large dI/dt stimulates the RLC resonant circuit into oscillatory ringing, which you can damp by twirling the knob of 20-turn trimmer potentiometer Rs. The whole arrangement uses test equipment you already have on your bench, today, without requiring you to fab a new PCB or source any new components.
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Thanks for the suggestion Mark, unfortunately the only signal generator I own is an iPhone app! I am just a curious hobbyist ( with no formal electronics training), exploring the wonderful world of electronics and learning why my friend's $10,000.00 hifi sounds so good!
Then applying what I learn into my cheaper audio equipment to improve the output.
The analogue scopes I have acquired along the way are an old 20 MHz generic Chinese brand and a 50mhz GOS-Instek. Both have dual channels. I have considered a signal generator but the prices are not affordable at this time.
I am fascinated by the experimentation re: the snubber circuits and Quasimodo! I take my hat off to you sir!!
Then applying what I learn into my cheaper audio equipment to improve the output.
The analogue scopes I have acquired along the way are an old 20 MHz generic Chinese brand and a 50mhz GOS-Instek. Both have dual channels. I have considered a signal generator but the prices are not affordable at this time.
I am fascinated by the experimentation re: the snubber circuits and Quasimodo! I take my hat off to you sir!!
Are there board for the Lite version available?
If so, would an iphone, using a signal generator app be good enough to use with the Lite version of Quasimodo?
What should I look for in a good used signal generator?
1. Not that I am aware of
2. You need frequency > 150 Hz; Amplitude > 10V into 600 ohm load. Check whether an iPhone can achieve these specs.
3. Start a new thread or piggyback onto an existing thread. Me, I bought a Gratten ATF20B new (Amazon link), and a Wavetek 395 used (documentation). Or you could spend two hours doing the circuit design of a 12V NE555 oscillator with discrete MOSFET output stage (BS250 + 2N7000), slap it together on your solderless breadboard, and implement Quasimodo ExtraLight without buying a signal generator at all. (But if you're going to build an oscillator + output driver on your protoboard you may as well build a full Quasimodo or Cheapomodo).
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