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  1. BobK

    LCD Display of Same Specification doesn't work

    What do you have on pin 3, which is usually a pot to adjust for contrast? If you have put a fixed voltage, the new display may need a different voltage. Bob
  2. BobK

    Voltage converter circuit

    I don't think that is what he wants, at least if he used the word analog correctly. I think he wants the 5V PWM signal to be converted to a voltage between 0 and 10V based on the duty cycle, which is not at all what he asked for in the original post. To do that, you need a low pass filter...
  3. BobK

    Voltage converter circuit

    Assuming DC, and output is signal level (neglible current out,) a simple op amp circuit would do this. You will need a single supply op amp and about 12V power, or a rail-rail op amp with a 10V power supply. Bob
  4. BobK

    MOSFET Issues

    Do you have a common ground between the pulse source and the gate? What is the voltage of the pulses? Bob
  5. BobK

    30W LED amplifier from 12V

    Sorry to disillusion you, but the colors will not be the same, or even remotely the same. I have used many different RGB LEDs and strips, and diffferent type needs a very different mix to achieve the same perceived color. Bob
  6. BobK

    Underdriven 12V LED chips in a 120VAC system

    I have not read the whole thread, so this might be repetitious, but... You have to understand the difference between the forward voltage of and LED and the operational voltage range of typical devices. I think you are interpreting 9-12V as being the range of safe operating voltages. That is...
  7. BobK

    Heated Clothing Potentiometer Help

    No, that is entirely the wrong thing. What kind of batteries do you have? Many have the protection circuit built in. Bob
  8. BobK

    Retail product that can supply 120V/30A from battery?

    What is this 120V 15A mains source? Typical residential wiring in the U.S., for newer houses is 200A with some 15A and some 20A outlets. Outlets for electric stoves are two-phase 50A.. Is is possible that all you need is new wiring to get the required current from your panel to where you want...
  9. BobK

    Open collector problem

    There are protection diodes on the inputs that conduct at 0.3V above Vdd. With a pullup of, say 10K, they will conduct well below their max current, but check the datasheet to be sure. Bob
  10. BobK

    Open collector problem

    Agree with Steve, all you need is a pullup to 5V. And I suspect that a normal output at 3.3V would work as well, the datasheet says 0.7 of supply, so 3.5V is guaranteed to work. Bob
  11. BobK

    Slayer Exciter with arcs?

    You are confusing radiating efficacy with resonance. Bob
  12. BobK

    Arduino system

    It doesn’t help any that you still haven’t answered my question after two attempts on my part. Bob
  13. BobK

    Slayer Exciter with arcs?

    No. The frequency is not determined by the length of wire, it is determined by the inductance and capacitance. Bob
  14. BobK

    Arduino system

    I assumed that. Did you understand my answer, which had a question in it? I'll try again. Do you expect to buy the system ready to go, are are you prepared to buy various parts, wire them together, and then write the code to do what you want to do? Bob
  15. BobK

    New Here, Considering Capacitors.

    For the most part, the capacitors you run across will not have enough voltage on them to harm you, but there are exceptions. For instance, do not open up a microwave oven and touch any capacitor terminals. The energy in a capacitor depends on its capacitance and the square of the voltage it is...
  16. BobK

    Arduino system

    Do you mean get, as in buy off the shelf a system that does exactly that? If so, the answer is probably no. Arduino is a DIY product, you buy a board, add perpherals, and program it to do what you want. You could probably find someone to build it for you on contract. Bob
  17. BobK

    Need device convert hdmi to composite signal

    What do you suggest I replace my oil burning hot water furnace with? bob
  18. BobK

    How to make setup and measure the frequency response for TDM MIC ( ICS-52000)

    Here is a starting point: https://en.wikipedia.org/wiki/Audio_analyzer Bob
  19. BobK

    Trigger a relay at certain voltage?

    Here is an updated circuit with a transistor driving the relay. You will almost certainly need this since comparators cannot provide enough current to drive anything but a very sensitive relay. Note that, because the transistor is an inverter, the + and - inputs of the comparator are...
  20. BobK

    Trigger a relay at certain voltage?

    Anything other than a comparator with hysteresis would likely result is less than satisfactory operation. Hysteresis allows you to define a "dead zone" around the trigger point so that, if the voltage is wavering right around 3V it will not keep triggering on and off. Here is a circuit: R2...
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