Search results

Search Forums New Posts
  1. Alec_t

    Oscillating pulse to stable

    I had a play with the Falstad circuit. Edit: Here's my mod
  2. Alec_t

    LTSpice "High-Z" output

    The built-in 'Help' (use the F1 key) actully helps ;).
  3. Alec_t

    Trickle Charge Batteries

    As explained on the other forum, you need a supply to handle the laser current plus a trickle charge.
  4. Alec_t

    Auto Intensity Control of LED Lights

    The collector current polarity depends on the transistor bias conditions.
  5. Alec_t

    LTSpice "High-Z" output

    Vhigh sets the logic-high voltage. Shouldn't you be setting the Rhigh and Rlow values?
  6. Alec_t

    Electromagnet with strength controlled by photoresistor

    Good luck with the project. BTW, those FETs should smell sweet if they're CHANEL :).
  7. Alec_t

    Oscillating pulse to stable

    If I've understood correctly I think this should do what you want, assuming the blinker provides 12V pulses. Each blink pulse switches on Q1 to discharge C1. While C1 voltage is low, M1 conducts to supply 12V to your 555 circuit. When blinking stops, C1 charges up to 12V via R1 and M1 turns off...
  8. Alec_t

    AC 0-20A Analog Panel Meter for use with house hold 120V / AC

    A rectifier bridge is necessary only if the meter is not a moving-iron type.
  9. Alec_t

    Distorted sound from a Electronic drum module Legacy dd502

    Good to hear you solved the problem.
  10. Alec_t

    Transistor to control resistance

    As the monitor is providing a constant 4.63mA to the sensor, the circuit below should give you the required monitor input from a 0-1.6V sensor. R1 and R2 set the scale and offset, so may need tweaking. I've assumed your supply voltage is a steady 12V, but smoothing/decoupling would be advisable.
  11. Alec_t

    TV set - I have broken it

    Presumably the rocking resulted in excess pressure on some component and broke it or dislodged it or cracked a circuit board trace? I'd recommend a VERY careful inspection of the whole set with a powerful magnifier.
  12. Alec_t

    AC 0-20A Analog Panel Meter for use with house hold 120V / AC

    Welcome to EP! You would have to find gauges rated for mains voltage and find a way of mounting and connecting to them without compromising insulation from mains voltage and hence safety.
  13. Alec_t

    Auto Intensity Control of LED Lights

    Welcome to EP! In the single-transistor circuit check the LED current. It is far too low. Neither circuit has hysteresis, so the LEDs are likely to flicker in response to small changes in ambient light level, e.g. at dusk and dawn or in cloudy weather.
  14. Alec_t

    First electronics repair question

    Welcome to EP! 104 indicates 0.1uF. It's an interference suppression cap. The diode is either for reverse polarity protection/prevention, if the original adapter was DC, or for half-wave rectification if the adapter was AC. You could try an extra diode or two in series with the motor to reduce...
  15. Alec_t

    Distorted sound from a Electronic drum module Legacy dd502

    Welcome to EP! The goo could be flux residue. I doubt the crystal is the culprit if you're getting sound, albeit distorted. I'd guess it's a power supply fault. Can't tell from the pic, but is the top of the big left-hand cap bulging at all?
  16. Alec_t

    Wien Bridge Oscillator

    Is this 'Homework help' or a school/college assignment?
  17. Alec_t

    Electromagnet with strength controlled by photoresistor

    Really? That's reinforcing bar, not wire :).
  18. Alec_t

    Wiring LEDs with different V & mA?

    Have you considered the safety aspects of this? UV radiation is damaging to eyes and skin. Safer to just use two different visible wavelengths.
  19. Alec_t

    Help with PIR Light circuit

    Welcome to EP! You would have to reverse-engineer the circuit to know how it could be modified. I doubt the schematic is publically available (but give Google a try if you have the board's serial number/ID).
  20. Alec_t

    Replacing a faulty SMPS

    Hmmm, that's a shame :(. Presumably it was/is something taking excessive current that caused the original SMPS to fail. When you say "two relays on the board where burned" do you know if the relay coils are still intact?
Top