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  1. Cirkit

    Insignia Flat Screen HDMI's Don't Work

    Before you suspect the HDMI IC, download the datasheet and check for the appropriate supply voltages to its pins. It looks as though there may be some regulators near it. Did you manage to find a service manual for the TV?
  2. Cirkit

    Satellite receiver Power supply higher voltages output

    Try measuring those voltages again with your black probe on the respective GND pins.
  3. Cirkit

    Fan making humming sound but not turning - CBB61?

    Thanks for the suggestion. I temporarily replaced the motor run capacitor with a Class-X2 one that I had of slightly higher capacitance and the fan worked! The one on the left is the original capacitor and the one on the right the X2 temporary one I tested: So what is the difference between...
  4. Cirkit

    Samsung Monitor repair

    Yes, they can be discharged while connected to the board. C1 is of most concern. Make sure that the mains power inlet is disconnected before going anywhere near the capacitor.
  5. Cirkit

    Fan making humming sound but not turning - CBB61?

    Thanks for your reply Minder. I measured resistances between the 4 colours on the 4-pole connector and also between both capacitor connections to each of the 4 wires (with the capacitor removed): 4-pole connector Green - Black 458Ω Green - Red 126Ω Green - Yellow 297Ω Black - Red 332Ω Black -...
  6. Cirkit

    Samsung Monitor repair

    You can measure the state of charge of the capacitors by setting your multimeter to the appropriate voltage setting and measuring across both terminals. If they still hold a charge, you can discharge with an automotive bulb, 5k to 10k power resistor or the blade of an old screwdriver (this...
  7. Cirkit

    Fan making humming sound but not turning - CBB61?

    I am trying to repair an air filter. The fan just makes a humming sound on any of the three speed settings but does not rotate. I've measured the 1.5µF motor capacitor (CBB61) and it's around 1.2µF. The tolerance of the capacitor is 5%. Would this be enough to prevent the motor from rotating...
  8. Cirkit

    Need advice on advancing from Arduino boards and next steps

    If you want to build WiFi and IoT projects but program in C, have a look at the ESP32 platform. There are plenty of IoT examples online.
  9. Cirkit

    Low noise power supply - linear?

    I'm just thinking power consumption if it were left on continuously. At what threshold would you consider using a switching design with an LDO?
  10. Cirkit

    Low noise power supply - linear?

    Is it possible to design a low noise, low ripple power supply using a switching design with an LDO? One typical application is for use with sensitive pre-amp circuits typically measuring pA/nA currents? The preference by many is to just use a linear power supply.
  11. Cirkit

    IR2153D

    Thanks for the pointer Alec_t, I totally overlooked the transistor mentioned in the datasheet across the timing cap! There is a G1 transistor across it with other discrete associated circuitry. I assume the transistor is an NPN with the collector connected to the CT pin and emitter to ground...
  12. Cirkit

    IR2153D

    I applied a current limit on the power supply and monitored the current draw as I was increasing the voltage beyond 15V. Am I right in assuming that there should be a waveform on LO when applying power between Vcc and COM?
  13. Cirkit

    IR2153D

    Thanks for your reply 73's de Edd. Looking at the datasheet, it seems to be similar to a 555. The IC should oscillate and produce a waveform on the LO output with just RT and CT connected. Should I therefore, assume it's faulty?
  14. Cirkit

    IR2153D

    I am trying to test a SMPS controller daughterboard from a compact PA system. The daughterboard is based around an IR2153D IC. I have removed the daughterboard from the main PCB and am attempting to test it in isolation. I have applied between 10-20V between Vcc and COM but do not see any...
  15. Cirkit

    18650 charging question

    If you are using 18650 cells without a protection board, you should use a dedicated protection board for 3 cells in series with balancing. Something like these: https://www.amazon.com/11-1V-Balance-Lithium-Battery-Protection/dp/B075D96HVV...
  16. Cirkit

    Sending sms with microcontroller

    Look up the SIM900. It's a GSM module that allows you to send SMS messages using AT commands. You will need to use the PIC to determine when the trigger condition occurs and to send the appropriate AT commands to the SIM900 module. There are plenty of tutorials online on how to use the SIM900...
  17. Cirkit

    Ceramic capacitors substitute

    The oscillator is used for a hardware PWM circuit to drive a motor. I have attached a schematic. The arrow points to where the output is taken.
  18. Cirkit

    Ceramic capacitors substitute

    The video was really useful, thanks! I think I'll probably opt for some automotive-qualified ceramic capacitors that can tolerate board flex such as the Vishay VJ-series or Murata VCJ-series. Edit: Just my luck, 4.7µF seems to be on back-order in both of the above series! However, there is a...
  19. Cirkit

    Ceramic capacitors substitute

    Hmm, I can't seem to find SMD film capacitors readily available in 4.7µF.
  20. Cirkit

    Ceramic capacitors substitute

    The oscillator frequency is <20Hz and I seem to recall reading that the slightly higher ESR in tantalums can help damp any ringing?
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