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  1. hevans1944

    Video signal amplifier.

    Edit: Sorry for the misinformation in my post #19: you can use CAT5 Ethernet cable, which consists of twisted pairs of insulated wires, for analog video.The pairs must be connected to impedance-matched differential transmitters and receivers to achieve a 500 foot distance without loss of chroma...
  2. hevans1944

    Video signal amplifier.

    @HANKMARS Re: Post #9. A balun! Do you even know what that is, or what it is used for? Show us a schematic of what you are trying to DO instead of how you think it should be done. If you are trying to move CCTV video from point A to point B, you use coaxial cable, either 75 Ω characteristic...
  3. hevans1944

    Create controlled 50v pulse

    Doubts should be based on good measurements and calculations, not speculation. Resistance and inductance have a huge effect on fast pulses, degrading both rise time and fall time. Do the math. I would also take a careful look at the LCR meter to make sure you are using it correctly because wire...
  4. hevans1944

    Create controlled 50v pulse

    It does appear that you are doing almost everything right, except I would opt for 10, 12, or 14 AWG bare copper wire for any circuit conducting LED current. 22 AWG is hook-up wire, not wire useful for large currents. And I am confused by the slow rise and fall times of the green oscilloscope...
  5. hevans1944

    Create controlled 50v pulse

    I agree 100%. It appears to me, from viewing your oscilloscope waveforms, that there are possibly two things going on here: (1) a delayed "turn on" caused by slow-rising current to the LED; and (2) a delayed "turn off" after an initial rapid decay in light output, perhaps caused by improper...
  6. hevans1944

    Create controlled 50v pulse

    That looks like a nice, fast, PIN photo-diode you found. Specs say it is capable of nanosecond response times, which are about three orders of magnitude faster than the pulse rise and fall times you measured with it. It is possible that the rise time was increased by parasitic inductance...
  7. hevans1944

    dc measuring

    It looks right to me, but perhaps you disagree and need help. Do you have a homework question? Some of us here may point you in the right direction, but we will not do your homework for you. Read posts #2 and #3 again.
  8. hevans1944

    Class AB Power Amplifier Design

    I did not say, and I hope no one thought I implied, that analog (electronics) was obsolete. The real world (except for certain quantum mechanical interactions) requires interfacing electronics with analog signals. It's just not done (much) anymore with discrete components. Certain vacuum tube...
  9. hevans1944

    Class AB Power Amplifier Design

    If beginning a design from scratch, consider using BJTs for class AB linear operation to obtain low distortion but at relatively modest power output and poor efficiency. Eliminating cross-over distortion can still be a tricky design problem so a distortion analyzer and perhaps an audio spectrum...
  10. hevans1944

    hall sensor and ssr

    @stark156: Sorry you interpreted my remarks as being rude. You come here on Wednesday, July 24, 2019, and post a question demonstrating your limited "general electrical knowledge." You describe, without providing any details, that you want to use a magnet and an unspecified Hall-effect sensor...
  11. hevans1944

    Does the TDA2030 need negative potential?

    You can buy circuit-board adapters that accept surface mount ICs and fan their leads out to through-hole pads. It is fairly easy to "drag solder" the surface mount component onto the adapter using an ordinary soldering tip and perhaps a head-mounted magnifier. Google for YouTube videos on how to...
  12. hevans1944

    hall sensor and ssr

    Why not include specific info with your initial query here? We don't have crystal balls that actually work, although I shine mine up once in awhile. There are a HUGE number of Hall-effect sensors available... pick one and tell us which one it is. Better yet, include a datasheet or a link to a...
  13. hevans1944

    12 MHz oscillator with a Voltage range 120V

    It has been more than a year since the first post on this thread. The OP disappeared the next day and has not been active here since then. So yet another "drive by" poster slinks back into their cave, unrewarded by an instant answer to their query...
  14. hevans1944

    10.7 MHz oscillator with transistor

    Much more clear? Not really. You still haven't provided a part number for the ceramic filter you used. But, as long as you are happy we are happy. I personally don't believe you know diddly about RF circuits, or their design, but generations of amateur experimenters before you didn't let that...
  15. hevans1944

    10.7 MHz oscillator with transistor

    How do you set the frequency of your "Small signal generator" to 10.7 MHz? I see no sign of the ceramic resonator thingy on your schematic in post #15. And why would you trust such a device to accurately provide 10.7 MHz? I thought they were more in the nature of band-pass filters, rather than...
  16. hevans1944

    Find a substitude mosfet

    This is wrong in so many ways. Go read some articles devoted to MOSFET construction. The body of the MOSFET is used to define, in conjunction with the gate electrode, a conduction channel, which can be either N-type or P-type. The width of this channel is influenced by the electrical field...
  17. hevans1944

    Find a substitude mosfet

    Yeah, at that price I would take the risk, for a buy of a few of them, that they are in fact "the real deal" and will work as advertised. But they are probably "clones," perhaps counterfeits if not licensed to be manufactured by a foreign fab, but not likely not. Wouldn't matter to me, if I were...
  18. hevans1944

    Find a substitude mosfet

    These MOSFETs have extremely low RDS(on) resistance at reasonable Vgs drive levels. Take a look at this DigiKey link for some possible substitutions with different VDS(max) and ID(max) specifications. Note that DigiKey offers FREE shipping to Israel for orders totaling more than $100...
  19. hevans1944

    Automatic Lighting with Raspberry PI

    Oh, yeah. Some of them hang around, ask questions but obviously pay no attention to our replies, and never explain just WTF they are really trying to DO. It is sometimes really difficult to distinguish this activity from trolling, but either one can best be handled by refusing to reply, the...
  20. hevans1944

    Automatic Lighting with Raspberry PI

    Yet another "drive by" poster looking for a quick answer. Not finding one, off to another forum perhaps...
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