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  1. Cirkit

    Touch activated torch - increase sensitivity

    Thanks for the suggestions. is there an alternative circuit/components that I can use that wouldn't be prone to static damage?
  2. Cirkit

    Touch activated torch - increase sensitivity

    Is there another way I could switch the LED with touch contacts without risking damage to a MOSFET? Could I use a low-power Op-Amp designed for battery powered circuits instead?
  3. Cirkit

    Touch activated torch - increase sensitivity

    Yes, the LED used illuminates sufficiently with a 3V CR2032 and a 150R resistor in series.
  4. Cirkit

    Touch activated torch - increase sensitivity

    Yes I did read his comments. So should I be looking at a transistor with integrated transient absorbers on the gate? What is the advantage of using a P-channel FET over an N-channel?
  5. Cirkit

    Touch activated torch - increase sensitivity

    The LED does light brightly when some people touch the contacts. The MOSFET has the marking 'A77E' on it. I'm guessing it's this part: http://p.globalsources.com/IMAGES/PDT/SPEC/255/K1007321255.pdf Would a darlington work down to lower voltages <3V?
  6. Cirkit

    Touch activated torch - increase sensitivity

    I've been given the attached circuit to improve. The LED should light when a finger is placed across two contacts spaced around 1cm apart. However, the LED doesn't light with everyone's skin. I have reduced the value of R2 from 150 Ohms to 47 Ohms which has slightly improved the sensitivity...
  7. Cirkit

    Understanding N-Channel MOSFETs

    Thanks for all the responses, I have a better understanding of what VGS to use in switching applications. My intention is to use a TO220 transistor for PWM dimming of LEDs. So switching, but at high frequency. The VGS would be from a microcontroller so I'm guessing no where near 10V. Can...
  8. Cirkit

    Understanding N-Channel MOSFETs

    I'm confused by the VGS(TH) and current rating of N Channel MOSFETs. For instance, the attached datasheet for a Fairchild FQPF20N06L quotes an ID current of 15.7A and a VGS(TH) of between (1.0V to 2.5V). However the graph in Figure 2 of the datasheet seems to indicate that a VGS voltage in...
  9. Cirkit

    Calculate how long a battery will feed a project

    What you need to do is measure the current with a multmeter in series with your WS2812B LED strip and circuit (microcontroller etc.) on the low voltage side. So in-between the output from your power supply and into your circuit/LED strip. If you can program the output from your circuit to all...
  10. Cirkit

    Calculate how long a battery will feed a project

    camilozk it seems that the wattage meter you are using is measuring the power consumption on the primary (mains voltage) side of the power supply that is powering your project/LED strips. You really need to monitor the power consumption on the secondary (low voltage) side to determine what...
  11. Cirkit

    mosfet power supply issue

    Hi Tamara, Welcome to the forum :) Would you be able to sketch how you have wired up the transistor, battery, motor and output from the remote transmitter? Maybe using the MOSFET as a witch might be the issue ;)
  12. Cirkit

    Arduino Not Communicating with Computer

    Are you saying it works fine with a power supply into the DC jack but doesn't work with a USB supply? If so, I would suspect T1 (FDN304V).
  13. Cirkit

    GSM/GPRS SIM900

    These links should help you: http://www.instructables.com/id/Sim900-GSM-module-interfacing-to-arduino/ http://linksprite.com/wiki/index.php5?title=SIM900_GPRS/GSM_Shield https://www.cooking-hacks.com/documentation/tutorials/gprs-gsm-quadband-module-arduino-raspberry-pi-tutorial-sim-900/
  14. Cirkit

    Making a Wireless Security Camera

    Looking at various YouTube videos for that backup transmitter, it seems that it will take a composite video input. So yes, it should work. However, the housing/antenna connector doesn't look waterproof.
  15. Cirkit

    Making a Wireless Security Camera

    Your best option would be to buy a cheap Wi-Fi camera and discard the camera part and connect the circuitry to your swpro-642cam. As *steve* mentioned above, you'd need to house the circuitry so that it is waterproof.
  16. Cirkit

    Removing components connected to large metal planes

    I am trying to rework some PCBs which have pogo pins that are attached to large metal planes with varying amounts of success. I have a high temperature tip however, when melting the solder while pulling the pins from the other side of the board, some of the pads lift. I have tried using flux...
  17. Cirkit

    Help with sourcing a DC socket, a quick question>

    Do you have any restrictions on size? If not, have you considered an XLR plug and socket: http://uk.rs-online.com/web/p/xlr-connectors/3297049/ http://uk.rs-online.com/web/p/xlr-connectors/3297033/ They are primarily used for professional audio connections but often also used for high...
  18. Cirkit

    Using a MOSFET instead of a BJT

    I have attached a circuit diagram of the output configuration. The inverting input is fed from an oscillator (~10Hz) and the non-inverting from another comparator Op-Amp circuit. The MOSFET will be driving a 3V motor with a maximum current of 100mA. There is a back EMF diode across the motor.
  19. Cirkit

    Using a MOSFET instead of a BJT

    I am currently redesigning a circuit and standardising on components as much as possible. Part of the circuit is an Op-Amp configuration to generate PWM pulses to drive a motor. I thought that substituting a BJT transistor on the output of an LMC6762 Op-Amp with a PMF370 would be a better...
  20. Cirkit

    What would be the effect If I change 4700uF capacitor to 18000uF?

    That power supply has split rails - positive and negative. You will need two capacitors as mentioned above in another post. If the exact value and voltage specification isn't available. you can go slightly higher.
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