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  1. Sunnysky

    Replace IGBTs FF200R12KS4 with FF300R12KS

    as @(*steve*) implied, switching speed or slew rate may be affected if driver does not have similar drop in resistor value to match drop in gate resistance. Most likely Ok. Thermal dynamics are unknown of complete circuit. However output will have corresponding improved lower Rce at 200amps...
  2. Sunnysky

    How to control the speed of a 24vdc pump from circulating water temperature?

    The circuit you have , has insuffient gain or sensitivity , thus excessive regulation error. Get a digital hermostat.
  3. Sunnysky

    Creating logic AND gate with 2N222 Transistor

    next
  4. Sunnysky

    Converting LED to Street Light?

    perhaps a better example . Here relay is inactive in light. Dark LDR turns off Q1 which turns On Q2 and relay using N.O. contact. FET's can also be used with some skills, or even CMOS Schmitt trigger and NPN. R3 provides positive feedback for hysteresis (aka backlash, deadzone, stable flip...
  5. Sunnysky

    Converting LED to Street Light?

    Sorry to say, hevans1944 schematic was a bad example. This is better schema of relay and it shows 1k input R needed to saturate Q with a 100Ω coil. If LDR cannot drive 1K then NG. Use this and imagine the coil has a conduction resistance which determines the operating current ..Most...
  6. Sunnysky

    Converting LED to Street Light?

    Your connections to relay look wrong. The coil should not have a centre tap unless it is a latching bipolar relay, which I doubt you have. Report relay p.n. and coil resistance. If coil is say 100Ω, the transistor switch needs a gain of more than 1k if biased by 100kΩ. This can only be done...
  7. Sunnysky

    Creating logic AND gate with 2N222 Transistor

    if you can read schematics on " google images" for ttl, you will know. This is why I included this question in all my interviews for design engineers.
  8. Sunnysky

    Creating logic AND gate with 2N222 Transistor

    nope. It is a single value , like a comparator with its refernce voltage. What is that TTL threshold? Hint if you measure the floating input, it happens to be a logic 1 if you see the output, but floating input is very close to the input threshold, which is the answer I expect. next...
  9. Sunnysky

    What fuse would a need?

    I now agree
  10. Sunnysky

    Sony TAF40 LED Repair

    He meant jumper the input to the chip on pin 8 not the driver outputs
  11. Sunnysky

    Power Relay needed

    not possible without boost convertor
  12. Sunnysky

    Need help selecting a transistor for a large power load

    kickback diodes should be across each coil in reverse polarity to applied voltage. coils may be wired to either common + or - then switches wired with common side to opposite polarity. So either switch V+ or gnd switch. Diodes only need to conduct coil current, so 14V/90Ω is low current for...
  13. Sunnysky

    Building a 1 kW automotive voltage regulator

    @GerCer Alternator rgulators are required to do more than charge batteries. There must be temperature regulation to prevent over-charging and deep sulphation as well as surge dump protection and field short circuit protection from causing max current output. • 80 V Load Dump • Temperature...
  14. Sunnysky

    Power Relay needed

    then do as I said before with separate battery and $5 budget
  15. Sunnysky

    Creating logic AND gate with 2N222 Transistor

    You are quite correct Bob . This also lowers the input voltage threshold from 2.7, which is ~Vbat/2 to 0.7V approx. and works. Smurph-> Logic designs for TTL have been around for eons but the standards for input voltage threshold have never changed for TTL. I suggest you follow Bob's mod and...
  16. Sunnysky

    Power Relay needed

    You dont seem to understand what I've told you. An Ultrabright Red LED needs 2V, (the old GaAs dim red 1.8) This means it goes out below 1.8V or barely visible Your circuit exceeds the recommended 20mA above 22V Do you understand Ohm's Law?
  17. Sunnysky

    Converting LED to Street Light?

    The LED draws ~20mA and the contacts require 100mA min to keep clean. The relay coil draws 360mW at rated V and your transistor cannot drive current required with ~10uA base current and hfe= 20-50 when near saturation thus only 200~500uA out. Thus Darlington or CMOS inverter required with...
  18. Sunnysky

    Converting LED to Street Light?

    remove relay and 9V and connect LED + 220R to 5V and collector. Anode to 5v and use two NPN in Darlington mode.
  19. Sunnysky

    Automotive coil on plug conversion HELP

    what makes you think you can make it work without an understanding of what is required? Hall sensor, PLL, vacuum phase control, SS coil drivers,,coils until you know how it works. Study existing ignition systems 1st.
  20. Sunnysky

    Converting LED to Street Light?

    Vbat is open and also reversed
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