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  1. dorke

    Loss of voltage with MOSFET

    Instead of letting everybody guess .o_O Please measure the voltages as in the pic and post them . All voltages referenced to GND of battery MOSFET and Motor and battery directly on pins.
  2. dorke

    Impedance of two stage amplifier

    Current source cascades, are not much different than voltage source cascades: when you drive an amp with a current source you need to use current dividers (parallel) instead of voltage dividers (series) and multiply the chain like you did for voltage sources. Rin, Rout are calculated the same...
  3. dorke

    Ultrasonic Metronome, or rangefinder transmitter

    1. First thing to do would be to check your dogs frequency range of hearing. It is very likely your dog can hear 40Khz(reports say up to 60Khz depending on breed and age). I guess that can be checked with a variable dog whistle 2.If your dog can indeed hear at 40KHz, you can work directly with...
  4. dorke

    Ultrasonic Metronome, or rangefinder transmitter

    Which transducer do you have? post it's datasheet please . .
  5. dorke

    Impedance of two stage amplifier

    thanks, It should be R6 indeed.
  6. dorke

    Impedance of two stage amplifier

    What model are you using for the Tr.? The Pi model has vbe in it not ib?
  7. dorke

    Impedance of two stage amplifier

    Here is a "simple" way to look at things. First note that the first stage isn't "common source" due to non-bypassed R4. KVL-loop 1 Vg1=Vin*(R2||R3)/(R1+R2||R3) loop 2 Vs1=R4*gm1*Vgs1 Vgs1=Vg1-Vs1=Vin*(R2||R3)/(R6+R2||R3) -R4*gm1*Vgs1 Vgs1(1+R4*gm1)=Vin*(R2||R3)/(R6+R2||R3)...
  8. dorke

    Impedance of two stage amplifier

    "Now, can I always assume that the RL1 will be the resistor between the two stages, here it is R11, plus input impedance of stage 2 regardless of how the connection from R11 is made?" Of course not! The way RL1 is connected matters. look ,here it is parallel :
  9. dorke

    Impedance of two stage amplifier

    You are correct, it will not work as intended,the gate bias is wrong, a cap is missing ! Here it is corrected:
  10. dorke

    College Project: Force Sensor displayed on 7 Segment

    Yes it is. ===>Attention<=== How can we create a "Guide Library" here for the benefit of all? Another separate entry under "resources" maybe? Who can actually do that?
  11. dorke

    College Project: Force Sensor displayed on 7 Segment

    Look here, chapter 4: Guide to measuring force Good luck
  12. dorke

    Simple stall over current 12v dc motor protection?

    What is the operating current of your motor? At what current do you wish to "disconnect the motor" and how fast? You can put a simple current limit in series with your motor, may do the job of protecting the motor...
  13. dorke

    Help required for Linear Power Supply build using LM317

    No you can't. The current is found in the datasheet under "adjustment pin current" It is a maximum of 100uA ,use this value to calculate Vout.
  14. dorke

    Help required for Linear Power Supply build using LM317

    BTW, What is the voltage your "small fan" needs? Most of all,Why does it have to be regulated???o_O
  15. dorke

    Help required for Linear Power Supply build using LM317

    1.Check that diode D1 isn't shorted or connected in reverse. 2.R2 value is too big change it to less than 5k ohm 3.Remove diode D2 ,in your circuit it serves no purpose. 4.Better use the values shown in the pic bellow,add input cap close to Vin pin of LM317 5.Take a good photo of your circuit...
  16. dorke

    12vMM..what does it mean?

    Please post the power supply page with the 12vMM signal. BTW, It looks like a truly terrible design...:(
  17. dorke

    Using seven segment displays with LED bar display drivers

    A simpler solution with "serial out data" can be done using this IC MC14499
  18. dorke

    Using seven segment displays with LED bar display drivers

    The task you want to implement is displaying a result in 3 digits. There are so many ways to do that. Let's assume the "direct parallel way" is not allowed. Assuming 4 bits per digit . One "simple" way is to use a series signal to "clock" the 12 bits into a shift register. That means...
  19. dorke

    Using seven segment displays with LED bar display drivers

    What exactly is "all programmable circuitry"? Is the use of the LM3914 mandatory? Doing that the way you do is like "scratching your right ear with your left foot":oops:
  20. dorke

    Looking for serial data logger, suggestions?

    If you can use a PC or laptop you will get absolute flexibility . The only thing you need is a free serial logging software like this one http://www.eltima.com/products/serial-port-monitor/
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