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  1. Sunnysky

    Need someone to check my circuit

    IF the tank is thermally insulated, then it is simple on/off with setpoint temp. Otherwise, you end up with stability issues needing complex PID gain adjustments. What temp? and what tolerance?
  2. Sunnysky

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    After repairs before inserting Batwing, note the caution :eek: symbols on Collectors of Q631,633. The current thru the collector R's must be low with the 2 POT's before installing the batwing next time. I.e. voltage drop equiv of 10-20mA
  3. Sunnysky

    how tolerant is USB?

    cable quality is critical at 2m distance
  4. Sunnysky

    Need someone to check my circuit

    I suspect 1500 W is overkill and will boil water on the surface of the element, which is why I Suggested an 800W insulated Rubber heater for the bottom like those used in water beds.
  5. Sunnysky

    Need someone to check my circuit

    Home thermostats don't use PID since the time constant is so long, just threshold detection with 0.5'C or 1'F hysteresis.
  6. Sunnysky

    Need someone to check my circuit

    I would use home thermostat with thermistor removed on shielded twisted pair and insert in water and use contact closure to drive a relay for 800W water bed heater.
  7. Sunnysky

    Supercapacitor Track Car Starter

    I don't think a bank of super caps would be feasible to support it. I = 200 A dt = 1 sec dv= 0.5V @ 12vdc Ic=C dv/dt thus C= 200A*1s/0.5V= 400F @ 15V rating call for an estimate , non stock http://www.digikey.com/product-detail/en/epcos-tdk/B48621A4455Q006/495-2068-ND/736058 450F 14V 1mΩ If...
  8. Sunnysky

    Need someone to check my circuit

    Your PID is an ON OFF control? or triac phase control? +- AC symbols are incorrect. It should be switching LINE and not NEUTRAL. Normally you just need a comparator , thermistor and pot with a Vref to drive a relay, since heating time is slow. If you use PID control then D gain must...
  9. Sunnysky

    Transistor LED circuit_LED not blinking

    this is not a good design, it might have been unstable with a weak battery with internal ESR. Try a better design. Try CMOS Schmitt Inverter with 1M feedback and 1uF on input to ground Prefer 5V 74AC14 and ~220 ohm R to LED to control current. HC14 will work but less current . This has...
  10. Sunnysky

    Amp In Protection Mode

    Sim for DC offset. Switch and 100k leakage pot with Bias and offset adjust included.
  11. Sunnysky

    For LEDs, is there a device that maintains a steady "power" output, interms of watts or amps?

    Read #10 until you understand
  12. Sunnysky

    Amp In Protection Mode

    Was the left channel tested with good parts and offset adjustment done?
  13. Sunnysky

    Amp In Protection Mode

    R627 must be reconnected properly in order for the Q603<>Q604 swap test to work! @dorke The loop must be closed. Your test method is at fault.
  14. Sunnysky

    Toshiba CRT TV fault... what could the problem be?

    I would inspect the flyback for dust and short out connection to doubler cap with a grounded alligator clip jumper to tip of a clean insulated screw driver. Try vacuum or clean doubler and flyback with paint brush and lots of isopropyl. alcohol. If not too dusty, toss it. Dry well with fan...
  15. Sunnysky

    Amp In Protection Mode

    The reasons are clear to me but I can demonstrate with a simulation if anyone indicates with a "like".
  16. Sunnysky

    ribbon code

    twisted pair out from current sense 10Ω R can use two probes in differential mode. single end to monitor Vdc.
  17. Sunnysky

    Technics SA-828 Receiver from 70s- Is it worth trying to save this aging patient?

    I am not sure if it has been suggested to replace all electrolytic caps yet. Faint audio suggest near full swing output stage oscillation from snubber cap failure. I still use my Technics for TV stereo amp and fixed it this way 10 yrs ago and still working.
  18. Sunnysky

    Common collector configuraton

    when driving linear loads , agreed. but not when driving diodes (LED) Then I consider base current must over driven with suitable gain reductions for Beta to ensure saturation and should use current limiting R. in either case CE or CC mode. But inverted CE is preferred with potentially lower...
  19. Sunnysky

    ribbon code

    3000uH would result in DCR with 3x DCR , unlikely a good solution. voltage drop on a 10 or 12 Ω replacement resistor for choke can help you evaluate faulty sensors for excess load current. A PTC could protect the part from overcurrent...
  20. Sunnysky

    ribbon code

    I would install a 10Ohm resistor and monitor voltage drop on a DSO scope on slow sweep to decide what is best for DCR. DCR* mA squared = P rating will be fixed for same size I recommend http://www.digikey.com/product-detail/en/bel-fuse-inc/0ZRC0015FF1E/507-1329-ND/1560184 in series with 4Ω...
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