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  1. Cirkit

    Hot air rework tool

    I bought a DrillPro hot air gun, but recently it fell apart when changing the nozzles. The internal glass insulator around the heating element broke off together with the outer metal casing which was crimped on at the base. The WEP 8508D was purchased as a replacement but the air compressor...
  2. Cirkit

    Green LED power consumption

    I did originally think that the resistor value was very high however, I presume it is to keep current consumption low and the LED is really bright anyway.
  3. Cirkit

    Green LED power consumption

    The current limit resistor is 1.2k. If overall power consumption is V*I and the forward voltage is higher but the current lower, the power drawn from the battery will be the same or greater? Or does the rate at which the battery will run flat only depend on the current through the LED and resistor?
  4. Cirkit

    Green LED power consumption

    I have replaced a red LED (Vf = 1.9V) in a circuit powered by a 3V battery supply with a green LED (Vf = 3.3V). Both LEDs have a specified If of 20mA. As the batteries are Lithium, the voltage starts off slightly higher at approximately 3.4V when new. The current through the green LED is much...
  5. Cirkit

    Convert PWM output to variable frequency

    That is an ingenious circuit Alec_t! Still trying to work out how the capacitor is discharged via D1? Edit: I think I've worked it out? The Schmitt trigger is inverting so as the capacitor charges to the lower threshold point, the output goes high and the lower leg of the capacitor is taken...
  6. Cirkit

    Convert PWM output to variable frequency

    Thanks again for your reply Fish4Fun. I feel at a real disadvantage not being to program micro-controllers :(. I am trying to learn on an MSP430 Launchpad but also have an Arduino Mini. I was looking at the Linear Tech. LTC6990 IC which is a voltage controlled silicon oscillator. The stepper...
  7. Cirkit

    help fixing netgear switching adapter

    You can continue to use the 12V 0.5A PSU and your router will probably work just fine. If you really want to repair the original PSU, I suggest you start by measuring the blue 1000µF capacitor which corresponds to the burn marks on the other side of the PCB and R18. Does your multimeter...
  8. Cirkit

    Convert PWM output to variable frequency

    Thanks both for your replies. I know that I could implement the whole circuit post the bridge sensor amplifier using a micro-controller however, I am still learning how to program them and am not very confident in doing so yet. Anyway, if I take the signal from the bridge sensor amplifier and...
  9. Cirkit

    Convert PWM output to variable frequency

    I have a circuit which outputs a PWM signal to control a motor's speed in response to an input sensor. The sensor amplifier, feedback circuit and PWM signal are based on a series of Op-Amps. I'd like to convert the PWM signal to a frequency variation to control a stepper motor driver based on...
  10. Cirkit

    SOT-32 package

    Mystery solved, the manufacturer had made a mistake in their literature. It should have indeed been SOT-23!
  11. Cirkit

    SOT-32 package

    Why is the SOT-32 package considered surface mount? It looks more like a through-hole package.
  12. Cirkit

    ISP and JTAG headers

    Good point! I guess I was initially expecting C/program code but it'll just be machine code!
  13. Cirkit

    ISP and JTAG headers

    Thanks Harald, I'll try and build a jig with Pogo pins on strip board. How long will I need to hold the pins on to read/program the micro-controller?
  14. Cirkit

    ISP and JTAG headers

    I'd rather not solder to the pads even temporarily. How would they connect to the header in a production environment? Could you please be more specific about what you meant by no? Will I not be able to read the code from the device?
  15. Cirkit

    ISP and JTAG headers

    Hello, I am fairly new to micro-controller programming. I am trying to read the code on a circuit containing an Atmel ATmega328P. Here is a photo of the ISP header on the board: How do I connect an Atmel programmer to the header without permanently soldering to it? Also, how will I know...
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