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  1. AnalogKid

    RGB LED controller current extension

    According to the user manual for your device, there needs to be a resistor in series with each LED string. This tells me that each output is a saturated N-channel MOSFET switch that is pulse width modulated. You cannot drive a TIP3055 with this type of output to do what you want. What is the...
  2. AnalogKid

    Astable 555 Circuit Problem

    R1 = 33K R2 = 10K C1 = 47 uF ak
  3. AnalogKid

    What are R5 and D1 used for?

    Without D1, changing either the trip point setting or the amount of hysteresis is a very messy calculation because the two are linked. With diode D1 in there, the trip point for increasing temperature has no hysteresis applied so it is set by R2 and R3 only. ak
  4. AnalogKid

    RGB LED controller current extension

    The circuit will not work as shown. Either the transistor collectors stay connected to +12V and the LEDs get connected to GND, or the LEDs stay connected to +12V and the transistor emitters get connected to GND. The actual changes are a bit more complex than that. But first, two very...
  5. AnalogKid

    Finding replacement for legacy Motorola Gate chip

    A 74AC00 has the right pinout, but runs on 5 V max. A 4011 will run on 3 to 18V, but has the wrong pinout. Neither has a 30 mA output stage. Is there any more information regarding the application circuit? ak
  6. AnalogKid

    Finding replacement for legacy Motorola Gate chip

    MC666 - the level translator of the beast. ak
  7. AnalogKid

    Termination block for module

    Similar units are made by Phoenix Contact. ak
  8. AnalogKid

    Rating of the Relay

    For some applications such as AC power to motors, the contacts arc as they separate. This arc burns off oxidation that would eventually form an insulating barrier over the contacts. Depending on the contact material, there can be a similar issue with low current DC signals. This is why many...
  9. AnalogKid

    Electric motor - one rotation then stop

    How do you reset a microswitch? ak
  10. AnalogKid

    Electric motor - one rotation then stop

    More stuff... This is a minimalist approach, courtesy of that thin sheet of glass in a MOSFET. Again, the circuit pulses the motor until it comes off the limit switch. The MOSFET pulse is approx. 200 ms. Step 3 in post #1 is "Power is switched off." Since the way this is done is a secret...
  11. AnalogKid

    Electric motor - one rotation then stop

    Not done yet...
  12. AnalogKid

    Electric motor - one rotation then stop

    No information on the top secret motor current spec, so I'm guessing 1 A. First pass at a Dose Motor controller. SW1 is a limit switch that is activated by a cam on the motor shaft. The motor opens the switch at the end of a cycle. When power is applied, the RC timer shorts out the switch...
  13. AnalogKid

    Drone flasher

    OK, last blast. Fixed the alarm chirp timing. With a 68 Hz clock freq, it now beeps/flashes for 1/8 second every 2 seconds, a good compromise between attention-getting and battery-saving. Initial turn-on delay is 2 minutes, then 2 minutes of alarms, 2 min. quiet, repeat. I never addressed...
  14. AnalogKid

    Drone flasher

    D1 is called a catch diode. When the counter output is high (5 V), the transistor side of the cap is at 0.7 V, the transistor Vbe. When the counter output goes low (0 V), the other side of the cap goes below ground until the diode conducts at -0.7 V. The cap discharges through the diode until...
  15. AnalogKid

    RF controller relay help

    There are many small remote control modules on ebay, some with 1 to 4 buttons and 1 to 4 relays. You don't give any details about voltages, currents, etc. But you can check them against the relay specs. If the relay can't handle it, use the remote control module relay to control a larger...
  16. AnalogKid

    High frequency pcb footprints

    Yes. For a reliable 433 MHz design: 1. It is important to use SMD devices. 2. The trace lengths, widths, thicknesses, and shapes all are very important. ak
  17. AnalogKid

    Electric motor - one rotation then stop

    A double-pole relay acting as a latch, triggered by a limit switch. ak
  18. AnalogKid

    PCB minimum thickness (rigid)

    The vast majority of 4-layer boards are 0.060"-0.062" thick, with some variability among vandors. Also, most vendors have a favorite stackup for non-critical designs. A 4-layer, low speed design wit buried vias - ??? ak
  19. AnalogKid

    Drone flasher

    OK, got it right this time. A MOSFET alarm transistor takes no energy to drive (compared to a BJT), It has a crisp square drive waveform instead of an R-C tail, and the input now works with either a DC or pulsed signal. The alarm chirps once per second, 2 minutes on and 2 minutes off. The...
  20. AnalogKid

    Drone flasher

    Here is an update to the schematic in post #7. Changing the position of the two transistors saves approx. 4 ws in base current energy per 24 hours. Also, C3 should be 220 uF for a 1/8 second beep/flash. ak
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