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Posts posted by HarryA

  1. You could use three 3.7v cells to make up a 11.1/12v battery. For example  three 9800 mAh would be; 9.8 Ah * 11.1 or 108.78 Watt hours. The valve only use 4.8 watts and the standby current for the IR unit is only 50 microAmps. For example:


    Finding a charger that charges an odd number of cells is a challenge. There are slot chargers that charge cells in parallel that would be helpful if you can find one.

    The 11.1 batteries as used for radio control airplanes are expense and require balanced chargers.

    My IR animal detector uses a standard 9v battery that lasts for many weeks.

  2. There are others who are more qualified than I on this circuit but not letting ignorance stand in my way I will continue anyway.

    In the various schematics U2 is connected to a transistor base through a 0, 22, or 1k ohm resistor. So it makes a difference which schematics you are referring to. At 1k the current from Q2 would be limited to 33v/1k or 33ma well within the 88ma max. of U2. Else for the 0 or 22 ohms I would wonder about diode D10 if it is shorted or not.

  3. At 3 seconds pulsing you could see that with a multimeter. I would start at the output of U2 looking for pulses; if so look at its input and likewise back to U1 and U2 outputs and inputs. The op amps U1 - U3 (TL081) are short circuit protected.

    "When shutdown occurs and less power is dissipated, the circuit cools as desired. The shutdown circuit is then disengaged and the circuit heats up. Again shutdown occurs and so forth."

  4. Q: Can the module amplify square wave or pulse? What is the module bandwidth?

    A: The module can amplify low-frequency square waves or pulses. Because it is an audio amplifier, the total bandwidth is not high. Signals within 100K can be amplified. The module is compatible with DC input.

    This is the over priced one with best Q/A


    The best price is 57.80$ Amazon.com  - actually it's 35.60$ plus 5$ s/h on Ebay

  5. The OPA548 op amp looks promising. It has up to 5 amperes output into 4 ohms or better. It can be bought in a complete amplifier see OPA348 on Ebay or Amazon.com just search for OPA548. The data sheet is here: https://www.ti.com/lit/ds/symlink/opa548.pdf

    As the amp can be used in a dc pwoer supply makes it look useful. If you have an Amazon account you can ask about the complete amplifier low frequency range else I can.OPA548.png.92f920c80613534325a6a7b3398c8060.png



  6. I am not to sure what your question is. Are you asking can IC by its self, not in a package, be connected to a circuit on a PCB? Yes but it would need power and ground, etc connections also. An IC in a package like a DIP can.

    For example in the CDI (capacitor discharge ignition) circuit,that I am currently working on, the optoisolator  (yellow) has the transistor directly connected to another device (MOSFET) on a another PCB.schematic.png.3e121ca1dbc3273198b5928af91f64ed.png

  7. Some years ago there was research on noise suppression by picking up a noise and playing it back 180 degrees out of phase. If you played a sound through two speakers connected out of phase, that is so when one cone came out while the other went in, would they tend to cancel? Thus creating a small cone of silence.            

  8. The font:



    "The font:" above is much lighter than the uploaded example.

    I could not see how to continue with the next image so I  am here. I am using an HP x20LED; I can not get to the model number. Lets see what others say. For login one does not see the "Display Name" nor the "password" text. Perhaps removing the dead space above it would help?



  9. Is it me or is the forum running out of toner? The font seems to be getting lighter over time. I can not adjust the browser to improve it.

    Also at login there is no physical response; the login area is down below the screen so one thinks nothing happened. Just trying to be helpful 😀

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