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  1. BobK

    Need help Transistor Touch Sensor

    The superbright LEDs are still usually rated at 20mA, but are insanely bright at that level. MOSFETSs can have very low on resistance, 100mΩ or less. At 1mA, this would be a loss of only 100uV. Bob
  2. BobK

    what is the threshold voltage for pmos transistor in Cmos inverter

    It is the voltage at which the transistor just begins to pass current. Bob
  3. BobK

    Need help Transistor Touch Sensor

    I made a suggestion of using a more efficient LED, Steve suggested using a red LED and a MOSFET for the switch. This combination of ideas should get you to a workable solution. Edit: And a resistor to limit current. For a red LED with typical forward voltage of 2 to get 1mA you would want...
  4. BobK

    Need help Transistor Touch Sensor

    Another case of battery abuse. If you look at the datasheet for the CR1216, it's rated capacity is at a draw of 0.046mA. 30mA would be 650 tines higher than this! It is also specified at 2.8mA pulsed for 2 seconds every 2 hours. Again way below the 30mA continuous that you want...
  5. BobK

    Radio Receiver Circuit.

    Antennae do not receive digital data. They receive an RF signal which might possibly have digital data encoded upon it in some way. Where is this digital data you want to receive coming from and how is it encoded? Bob
  6. BobK

    Which Speaker to use?

    ADRT's response is not correct. A higher resistance speaker will put less load on the amp. It is safe to hook up the 15Ω speaker, but the volume will probably be pretty low since it can only get about 1/4 of the power that a 4Ω speaker would get. Bob
  7. BobK

    DISPLAY 7 DIGIT DECIMAL VALUE ON 16X2 LCD

    Show us the code. Bob
  8. BobK

    Circuit/Schematic Simulation Software

    LTSPICE is a favorite of many forum members, and is free. Bob
  9. BobK

    Yes another NEWBIE question!

    http://www.ebay.com/itm/12v-10A-relay-multi-channel-wireless-RF-Remote-Control-Transmitter-Receiver-/361074098812?pt=Home_Automation_Controls_Touchscreens&hash=item5411b1827c Bob
  10. BobK

    Lab power supply from microwave transformer project.

    You really don't want a linear regulator for 50A. If it is dropping 2V, it would have to dissipate 100W. There are switching regulator controller ICs that will control an external MOSFET. This is what you should look into. Bob
  11. BobK

    Replacing a Photoresistor with Triac question

    Hmm. I wonder if the LED / photo-detector is used for isolation? It might not be safe to remove it. How about running the LED from a separate low voltage power supply, and varying the current in it to vary the speed? Bob
  12. BobK

    design score broad for a game

    It would work, but is overkill. A single transistor would work. Also note that an LM324 can only go to 2V less than the + power rail, so you would need 14V in to get 12V out. Bob
  13. BobK

    Trying to find an appropriate socket for an IC

    Dave, Click the last link. It shows a typical TQFP chip with the leads splaying out. The dimensions are exactly the same as the chip OP wants to use. And for $93 I don't think it is intended for chips that need a socket. It is a socket for chips that are normally soldered. Bob
  14. BobK

    Trying to find an appropriate socket for an IC

    Actually it looks like the socket from Mouser does fit the chip. But did you notice the price? Edit: Also, how do you expect the socket to help you? If you think you can avoid difficult soldering, the socket is going to be more difficult to solder than the chip. Bob
  15. BobK

    Noise in DC power supply

    It is not the regulator that is the problem, the transformer is unable to supply the power you need. Bob
  16. BobK

    Can you use serial communications on ethernet?

    If you have a serial port on your PC, all you need is some software to take serial port data and forward it over the internet. If you do not have a port, you can get a serial to USB converter that will give you a serial port. Bob
  17. BobK

    Do i need resistors?

    You most likely need a higher supply (5V) and transistors and resistors. A 3V micro is not going to be able to supply 20mA to a green or blue LED. Bob
  18. BobK

    Transistor Uses

    I think you would be best off to read a book covering electronics theory and practice and come to the forum when you don't understand something. It is not reasonable to ask us to teach you electronics, one paragraph at a time. See the "Book Reviews" sticky thread in this forum. The first part...
  19. BobK

    Moving electronic part/switch/relay - does this exist?

    Actually, there are such beasts. Look up "latching solenoids". But I don't think you will find one in the size the OP wants. Bob
  20. BobK

    battery charging / testing multimeter question

    There are plenty of inexpensive chargers for 18650 batteries out there. Buy one. Bob
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