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  1. hevans1944

    Help with connecting&controlling THK kr20 Linear Actuator

    The six-wire ribbon cable appears to connect (also) to a 9-pin DB9 connector, pin-out unknown, sex of connector unknown (but typically would be male pins for application of power). The DB9 connector is NOT a serial port connector. The 6-pin gray female connector would typically mate with square...
  2. hevans1944

    Sound Sensor

    Clearly you need a microphone, but these are available in a bewildering number of styles and technologies. The widest dynamic range is probably the moving coil microphone, essentially a miniature loudspeaker used "backwards" so movement in a strong magnetic field of the coil, attached to a...
  3. hevans1944

    Help amplifying a tiny current

    It's worth trying. That would only add only six milliamperes to the sink current when DO is low but it would drop Vcc = 6 V down to about 1.8 V when DO is high, (6)(440/1440) = 1.8. That may or may not be enough to reliably turn the opto-isolator on. This is assuming the SSR control inputs are...
  4. hevans1944

    Successfully unsoldering a big relay

    As a last resort, you could cut the relay off at its base using a fine-toothed coping saw. That will expose the terminals for removal one at a time. Make sure you really need to replace the relay, and have a replacement on hand, before sacrificing the original relay.
  5. hevans1944

    Connecting cable to a pcb pin with electrical tape

    Real Red Necks use DUCK tape.:p
  6. hevans1944

    Help amplifying a tiny current

    Typically the SSRs have an LED in an opto-coupler input that needs a current limiting resistor. Sometimes they add an inverse-parallel diode across the LED to protect against reverse polarity. Depending on the minimum control voltage, there may also be a visible LED in series with the...
  7. hevans1944

    Designing a Time Delayed Relay

    Looking good! Very professional looking job. I want one!:D
  8. hevans1944

    90v/100a DC Power Supply

    Twenty years ago? I was talking about my observations as a kid from the 1950s, not the 1990s. AFAIK, everything was manual control with analog indicators, and perhaps some Honeywell pneumatic controllers and strip-chart pen-and-ink recorders to track process variables. Heating and cracking crude...
  9. hevans1944

    Help amplifying a tiny current

    Yes, the transistor is necessary to provide both operating voltage and current to the low-impedance (440 Ω) control input terminals of the SSR. The existing 10 kΩ internal "pull-up" resistor connected between Vcc and DO will act as a voltage divider to the 440 Ω input impedance of the SSR...
  10. hevans1944

    Designing a Time Delayed Relay

    It is unfortunate that the actual versus predicted values turned out to be so different, but the "proof is in the pudding" so you have to go with what works. Since this is a one-off project, there seems to be little incentive to delve deeper into the "problem," except for academic curiosity...
  11. hevans1944

    Help amplifying a tiny current

    With the SSR in the transistor collector circuit, there should be no problem lighting up an LED that might be present on the SSR. Nice feature, that.
  12. hevans1944

    Help amplifying a tiny current

    You don't need to know much to get your circuit working. The SSR will work "better" than a relay. But while you are waiting for it to arrive, why not try adding an external 2000 ohm resistor from Vcc to DO to guarantee the transistor will be driven fully on (into saturation) when DO goes high...
  13. hevans1944

    It's 1890!

    Antibiotics! Yikes! I ain't goin' back to 1890. Period. End of Story. You young whippersnappers go fer it.
  14. hevans1944

    90v/100a DC Power Supply

    Oil refinery operator, huh? I grew up near oil refineries in southwest Louisiana and southeastern Texas, but back in the day it took a boatload of people to run them. I guess everything is computerized and networked today, so just a few people are needed onsite to maybe swap out a flow or...
  15. hevans1944

    Help amplifying a tiny current

    This is true. But see this: "it (the LED) seems to go off when the temperature goes above setting, which is when i would like the relay to activate" which was re-iterated in post #35 and confirmed by Steve in post #36: LED OFF, RELAY ON. So I am thinking with the relay de-actuated, and the...
  16. hevans1944

    90v/100a DC Power Supply

    Welcome to Electronics Point! That's pretty ambitious for someone new to electronics. That's nice, but you have failed to tell us what you are trying to DO. You have told us what you think is how to do it (whatever it may be) by saying "will receive voltage data (what's that?) from sensor...
  17. hevans1944

    90v/100a DC Power Supply

    If you sell it on Amazon, maybe they could deliver it with one of their 'copter drone thingys...
  18. hevans1944

    Another find at the Habitat for Humanity Restore

    At work, late in the previous century, I found something similar stuffed away in a corner. If was a three-phase version with one more stack of toroidal auto-transformer ganged with the other two on a common shaft, along with some sort of inductor in a black bakelite case on each one, purpose...
  19. hevans1944

    It's 1890!

    Knowledge and skills are the only reliable things you can take back to 1890. Well, maybe a good anvil and steel hammer if you want to ply a blacksmith trade. Plenty of horses in 1890 that need new shoes, and a forge is pretty easy to make. Maybe need a wheeled cart for the anvil, depending on...
  20. hevans1944

    Help amplifying a tiny current

    It does output a positive current from Vcc through the on-board 10 kΩ "pull-up" resistor when the open-collector LM393 comparator goes "high" and thereby removes the path to common for the LED, turning the LED OFF. I am assuming you want the relay to actuate when that happens. Unfortunately, in...
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