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  1. Alec_t

    DC Voltage conversion for miniature bulbs?

    I suppose one of these (600mW) isn't powerful enough? If the densitometer already has a 12V supply, why do you need to step up from 3V?
  2. Alec_t

    DC Voltage conversion for miniature bulbs?

    If that has enough oomph to power a 3W 12V bulb in place of the 3V one you should be home and dry. A light pipe might be handy if you need to position the (larger) bulb other than in the original bulb's position.
  3. Alec_t

    DC Voltage conversion for miniature bulbs?

    How important is colour temperature? I'm guessing (could be wrong) that using a 6/12V bulb instead of a 3V one, even if of the same wattage, may not result in the same colour temperature, because of the difference in the thermal mass of the filaments.
  4. Alec_t

    in-car (passenger) electronic device use: resonance vibration natural frequency

    I would think that will increase the risk of damage to the pcb, not reduce it. Consider what will happen if you brake sharply or the car hits something. All that extra weight will have considerable kinetic energy, some (much?) of which will be dissipated in the pcb and its components. What...
  5. Alec_t

    heat emitted by LED signs and lights.

    Welcome to EP! (1-e)*p, where e is the sign/light efficiency and p is the input power. Yes. Ask a sign/light manufacturer. Conventional sign/light power (CP) minus LED power (LP). Probably Watts. 100*(CP-LP)/CP. It's a percentage
  6. Alec_t

    Kustom organ repair of funky contacts

    As well as a picture, dimensions would help too.
  7. Alec_t

    Lm13700 LTSpice Sim Help

    Like you, I failed to get your sim of the VCO in the datasheet to run. However, it can be made to run with the following changes (I daresay other changes would work too):- 1) Reduce V3 to 1V, 2) Increase C1 to 100n, 3) Add the directive ".options gmin=1e-7" to the schematic.
  8. Alec_t

    High voltage: Can't stop electricity from jumping over resistors

    Assuming your 'bunch' is 6, then each resistor will have 50kV/6 = 8.3kV across it. That seems a helluva lot for a 0.89" resistor. Farnell (for example), doesn't list any 100k resistors with a voltage rating >5kV.
  9. Alec_t

    Lm13700 LTSpice Sim Help

    Please post your .asc file here.
  10. Alec_t

    High voltage: Can't stop electricity from jumping over resistors

    What is the voltage rating of each resistor?
  11. Alec_t

    1n4007 is getting hot

    At 1A the rated Vf is about 0.9V, so the dissipation is 0.9W. Expect the diode to get uncomfortably hot.
  12. Alec_t

    Solenoid Specification Forces

    A simple lever could overcome that. The actuator would have the advantage of a constant force over the distance.
  13. Alec_t

    Solenoid Specification Forces

    This calculator may be of some use for an estimate of the force, but factors such as the plunger shape also play a part. Have you considered using a linear actuator instead?
  14. Alec_t

    555 timer to turn on 2nd 555 timer

    C1 and the 100k pot set the delay time. C2 is a 'decoupling' cap which holds a reservoir of charge to help out the battery when there is a sudden current demand. It is good practice to have such a decoupling cap with most ICs. C3 is the oscillator timing cap. C3 + R5 set the servo pulse...
  15. Alec_t

    Trying to power late grandmother's portable TV

    Welcome to EP! Googling 'DC power plug adapter' should find you something. You need to know the inside and outside diameters of the plug. 2.1mm and 2.5mm are common inside diameters.
  16. Alec_t

    555 Timer IC monostable

    Welcome to EP! 'Ground' is an arbitrary reference potential in a circuit. Your body provides a resistive path to true earth ground. For help re the switch and the LED you need to post (using the 'Upload a file' button) the schematic of your circuit. We're not psychic :).
  17. Alec_t

    555 timer to turn on 2nd 555 timer

    As you found, consulting the relevant datasheets is essential before/when working with components you're unfamiliar with :). Hey, if it works for you, it works! The non-reset bug could be due to a poor contact in the breadboard. Poor contact is a common problem with breadboards. Building the...
  18. Alec_t

    I Need Help With My 555 Monostable Circuit Please

    I hope you remembered to keep the reverse-biased diode across the relay coil? Without that the 555 probably won't survive.
  19. Alec_t

    Looking for a replacement of NE38B Neon Indicator Bulb

    Welcome to EP! Looks like the three neons together are acting as a voltage reference (about 3 x 80V = 240V) for voltage limiting/stabilising purposes. If you can't get exact replacements you could try common mains indicator neons.
  20. Alec_t

    555 timer to turn on 2nd 555 timer

    You have pin 3 going to C3 but not to R5, R8 and the 'width pot'. Pin 5 should not go to pin 8. Pin 6 should not go to pin 7 but should go to pin 8. Pin 7 should go to ground instead of to pin 9. Pin 11 should go to pin 13. Pin 14 should go to the +ve rail. C2 should connect between the +ve rail...
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