Jump to content

JoaMat

High Rollers
  • Posts

    1,420
  • Joined

  • Last visited

  • Days Won

    16

Everything posted by JoaMat

  1. It’s not very clear in the schematic above (I’m sorry), but D15 and D16 is a bi color LED with common cathode. Below the two LEDs are replaced with a bi color device. The purpose of the 555 is make the LED red when relay is disengaged and green when engaged. This is the way I found to get a simple red/green indicator working.
  2. A slightly reworked “Dynahi smd” board. Balance and offset trimmers removed. Now servo on each side that bring the offsets to ground potential. Bias trimmers moved to north for easier accessibility “in flight”. This is a "solder and play" board. No set up procedures required, except to turn bias trimmers to desired bias. At least that’s the idea.
  3. My latest schematics - essentially a copy of the original. See this Protector 3 gerbers by Kevin Gilmore protect3.zip.
  4. Yes, of course, stn0214. My mistake – I shouldn't rely on memory solely.
  5. If it’s ksc5026 in KGSShv style power supply you can probably use stn0216 stn0214 intstead. Solder it standing on the to126 pads (might be to220 pads on your board?). Power dissipation there is something like 40 – 60 mW, I think.
  6. During the last weeks I’ve built a few versions of the headphone protector. One small problem is voltage regulators, 7812 and 7912. Output voltages might differ more than 100mV from “specified “. 7812 at +12.1V and 7912 at -11,9V will move intended references 100mV. To tackle the problem, I made this resistor string. With above resistor string I can handle any deviations of the voltage regulators up to 200mV. If you want something else than +/-60mV trigger points, change the 1K resistor. 2K instead of 1K gives you +/-120mV. I’ve enjoyed working with this protector project a lot. Thanks for designing this Headphone Protector, Kevin.
  7. Next build – remove R1 ( don’t understand why I put it there – maybe because I’m an amateur) and R2 value is far too low, unless you want 40 mA through LED, so I switched to 1K. Small board 19mm x 15mm with the 555, a small PNP , three resistors and of course the bi color LED. Works perfect.
  8. Nightly build Red LED indicates disengaged headphone. The green LED indicates power is on. Here red is out and headphone is connected. Next build… …a bi-color LED to replace the two above LEDs.
  9. Headphone protector installed and working. Delay time is 15 seconds, and it disconnects when offset is more than approximately +/-70 mV.
  10. Thanks James, your schematics gives a clear picture how to switch to KSA1220 and KSC2690. Unfortunately, it seems that KSA1220 is out of business. Fortunately, TTA004 and TTC004 can replace KSA1220 respectively KSC2690.
  11. Kind of, mains in at blue tblock and and +/-24V out at the other corner. Can’t be easier.
  12. Just move the two right legs on step to the left and swing the left leg all the way to the right…
  13. SMPS300R , bought from Audiophonics - nice company, next day delivery from France to Sweden.
  14. My CFA3smd something, now powered from a switched mode power supply and equipped with a headphone protector. I’ll test this for a while and if I like it I might build a decent cage for it. Else I’ve a growing "good to have" closet.
  15. It’s soldered by hand. I’ve tried hot air, but I prefer a solder pen and tweezer - gives me better control I think.
  16. Seems to work. The red LED turns off and on correctly. Red light means everything is OK – off means something is bad. A green LED might be more appropriate. The short uninsulated wires, one each side, is not to correct a mistake. It was the only way I find to get it working. The board has 19 vias. I did one mistake though. I gave the mosfet driving the relay a wrong footprint, but fortunately it was possible improvise… now it works as it should. I’m waiting for the relay. Omron G6S-2G – surface mounted, good for 2 A.
  17. Popped up at Qobuz grand selection. I enjoyed it.
  18. Here is a rebuild Dynahi, now a CFA3 something. CFA3smd engraved on back side of the Dynahi front panel. A green LED in the small S. Diagram of bias (in mA for the first 40 minutes from power on) for servo respective no servo. I think that with the servo it’s possible to build this with just 4 transistors instead of 14 (per channel) on heat sink – time will tell.
  19. A working stereo CFA3 something. I’ll wait with chassis until I’m confident it won’t “runaway”. So, now it’s on the floor in our living room. My wife is a very understanding woman.
  20. Issue with bais above solved. Reason was a misaligned 600pF smd capacitor shorted a trace to ground. When powering the amplifier, it takes some seconds until the bais raises to set value. One side tends to wait much longer than then others. Offsets all channels are close to zero – a few mV at most. No hurry with headphone protection...
  21. Still too early say anything about stability. Yesterday I built another board. One side worked as supposed but the other side’s bais was stuck at zero whatever I did. When I touched a few places on the board with a test pin the PSU’s current raised so the current limiter kicked in. This happened even with an unconnected test pin. I can build very odd things… that I don't understand. Bottom line: JoaMat should build himself a Headphone Protector.
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.