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  1. C

    Potentiometer as a Variable Resistor

    If you want to replace a 25 ohm rheostat with a 5k pot you need a transistor connected to the pot. The pot should 500R
  2. C

    Two capacitors in parallel - High or Low ESR?

    You actually want capacitors with high ripple current capability. This really means looking at the size and selecting the biggest capacitor for the capacity and voltage-rating that you choose. Ripple means how hot they will get when in use.
  3. C

    Negative Voltage - Theory Question

    But you have to remember, it is 12v higher than the earth rail and 12v lower than the earth rail.
  4. C

    Problems charging a garden tractor battery

    There is no problem at all with spiking a battery. You can see by the spark, how much current is flowing. I have done it for 40 years and I still have half my face to prove it is not all that dangerous.
  5. C

    Problems charging a garden tractor battery

    You get two car batteries in series and pulse the tractor battery. The try to charge the battery 3 times and test it with the lamps. If it does not start the tractor after 3 tries, one or more cells have sulphated up.
  6. C

    Are tantalum caps sometimes used as a circuit protector ?

    "you degraded the regulated 12V voltage of the circuit." That's not the full analysis. The low impedance of the tantalum is designed to prevent the regulator producing high frequency oscillations in the MHz range. We do not know if the regulator will do this and we don't know how important...
  7. C

    project help

    100mm x 50mm 7-segment displays. RF link to 50 metres.
  8. C

    project help

    I have a two digit counter with large displays and RF link and I blink the displays too. It is available as a kit.
  9. C

    Volts to ohms for fuel sender

    Instead of messing around with all these values, you simply get a LED bargraph driver and connect the output of the sender to the input of the chip via resistors and a trim pot. Now fill the tank and watch the LEDs increase. See how linear the results are. You can design the bargrah to show...
  10. C

    My first ever project......your thoughts please.

    Flashing LEDs like to drop a voltage a little bit higher than 3v. You can get all sorts of flashing LEDs on eBay that blink and flash and flicker and change colour.
  11. C

    Question about DC and Coils and LED.

    TRANSISTOR and LED TESTER - 3 Here is another transistor tester. And it also tests LEDs. See the full project: Transistor Tester This circuit is basically a Joule Thief design with the coil (actually a transformer) increasing the 1.5v supply to a higher voltage to illuminate one or two LEDs in...
  12. C

    Question about DC and Coils and LED.

    You all missed the point and did not provide a solution. If you place the two coils very close together and tap the end of one coil on the battery very quickly, the LED will illuminate a small amount. This is due to two things. Firstly, the transfer of energy from one coil to other only takes...
  13. C

    Question about DC and Coils and LED.

    "Connecting the led through a wire to a 9V Battery guarantees the LED is a goner..." Who said he did that ????
  14. C

    Question about DC and Coils and LED.

    "Yes you are,you have just destroyed your Led!" How did you work that out ?????????
  15. C

    Wanted: Electronics Technical Writer Required

    I can write real good electronic article. Wot do U want ritten?
  16. C

    Circuit trigger on specific preset sound

    I have a tone operated circuit using a PIC chip. You just need to tell the chip what frequency it needs to listen to and it activates an output.
  17. C

    dc motor questions

    "If you use a resistor to slow the motor down, the power dissipated in the resistor will decrease battery life." Where do you get this gobbledygook from?
  18. C

    78l33 circuit regulator, thought it would drop a 5v voltage to 3.3 v but no!

    The first thing to do is answer this question: How much current do you need? You have been running around in circles with no possibility of getting a solution.
  19. C

    Uprate a model servo

    Take this linear actuator and connect the output to the winch and then take the output of the electronics to a bridge to drive your motor. It's that simple.
  20. C

    LED Fade Circuit

    If you had 100 watts of lighting, your truck would be illuminated like a kitchen.
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