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  1. Herschel Peeler

    Common Base

    Okay, having flipped it, go back to your questions. What will the voltage on the emitter be? Assuming the output is on the collector (it doesn't show that either). Shorting the transistor (transistor on and in saturation) what will the voltage on the collector be? What is the maximum collector...
  2. Herschel Peeler

    Common Base

    You have an NPN transistor with the emitter more positive than the base. It will never turn on. Bad picture.
  3. Herschel Peeler

    How to test a capacitor

    I'm 10 years out of touch with such things. Google capacitor tester or maybe some of those here can suggest something.
  4. Herschel Peeler

    How to test a capacitor

    depending on the size of the capacitor, that is true. Yes, ,buying a capacitor tester is a better idea.
  5. Herschel Peeler

    How to test a capacitor

    Is it shorted? If so it's bad. You could undo one side of larger capacitors and see if they hold a charge. Charge it up on Ohms scale. Switch to voltage and see if it held a voltage.
  6. Herschel Peeler

    microFarad

    -6 for micro
  7. Herschel Peeler

    Common Base

    If you take the transistor out you lose the E-B voltage. So short Emitter to Collector. W Is the circuit drawn correctly? I would expect the higher resistor value to be on the Base. NPN or PNP transistor? I would expect a circuit more like this.
  8. Herschel Peeler

    Cheapest way to get data from multiple(100s) of sensors?

    Analog multiplexers? Thirteen 8-bit analog multiplexers, like CD4051. 7 Digital outputs to select the device and which input. One analog input. 4 bit to 1 of 16 decoder (or two 3 bit to 1 of 8 decoders) to select the devices. RGB LEDs? Maybe IR LEDs matching the sensitivity of the IR sensors..
  9. Herschel Peeler

    A little help on Sine Waves.

    Trig tables??? Find the Sine of 36 degrees, then times100 V. Calculator??? SIN(36)*100 Do you have Microsoft Excel? It does trig functions. I suppose most other spreadsheets do, also. Do you have a Windows computer? It has a built-in scientific calculator. "View", "scientific", "degrees", 36...
  10. Herschel Peeler

    Looking for cheap ammeter that measure the smallest amp

    My $3.95 DMM goes down to a 200 μA scale. DT-830B.
  11. Herschel Peeler

    Determine the unknown voltage in an ideal Op-Amp circuit

    I guess that is what he was looking for.
  12. Herschel Peeler

    Determine the unknown voltage in an ideal Op-Amp circuit

    Okay. Backing off. In the case at hand his problem was not seeing a probes to find the answer, not just not having the answer. Show him what a process is like. You could ask him questions for a week going back and forth and get nowhere. .
  13. Herschel Peeler

    Determine the unknown voltage in an ideal Op-Amp circuit

    Banned for showing him how to solve the problem? Fine, I will stay out of the homework stuff.
  14. Herschel Peeler

    Determine the unknown voltage in an ideal Op-Amp circuit

    Not much math required. What is the circuit? Inverting summing circuit. Sums the incoming currents. Realize ... Rf = Ri, Second Ri is 1/2 of Ri Known input is 1 V. Output is 2 V. Since Rf = Ri gain is -1. Input current know is 1V/Ri. If that were the only input the output would be -1 V. Since...
  15. Herschel Peeler

    Determine the unknown voltage in an ideal Op-Amp circuit

    Formula? What formula? :-) I guess I could come up with one but it would only be meaningful for this specific question and be of no use in the real world. Understand how the circuit works. See the simple question intended.
  16. Herschel Peeler

    Determine the unknown voltage in an ideal Op-Amp circuit

    The lesson was not in finding a formula to solve the problem but in seeing the simple process of a solution. See the simple question. His approach was what was hindering him. hint ... Resistor values were not important since they were not included. Forget the math. Understanding how the circuit...
  17. Herschel Peeler

    Determine the unknown voltage in an ideal Op-Amp circuit

    l 500 mV With no second input voltage and R = R the output would be -1 V. To double the output voltage (and feedback current) you need to double the input current sum. Don't imagine it to be so hard. See the simple lesson intended.
  18. Herschel Peeler

    Battery stuff, need help!!!

    What the battery will put out is a characteristic of the battery. You could charge it at 1 Amp and get 10 Amps out. It depends on the battery. Keep in mind charging current is not always consistent. Charging from a power supply (constant voltage source) as the battery charges up charge current...
  19. Herschel Peeler

    Oscillating Leds circuit anywhere?

    450 to 600 is a very broad range. It is pretty much the colors of everything in your garden. Perhaps if you made the lights brighter than anything else in the area it might attract them. How fast did you think about the flashing? One pulse per second for each color?
  20. Herschel Peeler

    question about 2N2222

    A 2N2222 does not turn on all the way down to zero ohms, so yes there is a limit on the low side. It will not tolerate voltages over a certain voltage, so yes there is a limit on the high side also.
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