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  1. (*steve*)

    Charging Circuit

    It might be worth looking at this thread. We reverse engineered a circuit designed to allow the charging of supercaps up to a certain voltage. There was also a board shown which turned on a LED when the cap was charged. It seems much simpler than the circuit given in this thread. If you can...
  2. (*steve*)

    74HC oscillator, how fast?

    So 84MHz at 5V isn't bad :-).
  3. (*steve*)

    Led Flashlight Help

    The best solution is to get an SMPS with an adjustable current limit in addition to the output voltage setting. Start with the voltage set to something safe (like 4V) and the current set to close to the minimum. Apply power and wind up the current until the torch is the correct brightness...
  4. (*steve*)

    Pavilion 560w MB w/bulging caps

    I feel quite cromulent, thanks. Great. What are their specs like? What's the ESR quoted as being? What about the ripple current rating? Do you think those ratings will be sufficient? A mear [sic] $10 isn't cheap if they only last a month. No, as long as they fit. Also, it looks like...
  5. (*steve*)

    Color Sensor

    Yet again, I think it's time that you let us in on what the problem is you're trying to solve. While your solution might turn out to be the best one, it might also be unnecessarily complex. What are you trying to achieve?
  6. (*steve*)

    Identifying blown transistors

    The good news is that they look like single MOSFETs. What were you doing? Did you connect a high voltage source to allow you to recharge the caps quickly? Are you sure the 100k resistor is fried? It's a high value and they don't normally get damaged. However, if the gate is now connected to...
  7. (*steve*)

    Identifying blown transistors

    Before you go too far, is your unit under warranty? Do you have access to another unit that's not dead? Has anyone done a treasurer and shown this in detail?
  8. (*steve*)

    Pavilion 560w MB w/bulging caps

    The first quote is @tedstruk's reply to someone else having a problem with a motherboard. He posted it less than 24 hours ago. You can't help but wonder at the inconsistency.
  9. (*steve*)

    Pavilion 560w MB w/bulging caps

    Is there any reason not to take your own advice? I really hate to sat this stuff. I have found from past experience that motherboards are extremely touchy when they fail. It is easier and less costly to replace the motherboard than to try and find a bad component. Most are assembled by robots...
  10. (*steve*)

    Micronta VOM

    Also, it might be worth checking out this http://www.eevblog.com/forum/repair/radio-shack-(micronta)-multitester-model-no-22-216/. It's not your model, but as noted from the photos, it appears to have a fuse in the current ranges. Maybe yours does too? Note that you might have faults aside...
  11. (*steve*)

    Micronta VOM

    Also, if you can post a photo of the board, that would be of great assistance.
  12. (*steve*)

    Micronta VOM

    If it's a voltage range that is affected: I would carefully differ one end of this damaged resistor and measure it's value (with another meter). Then solder it back into place again. With the meter in the known faulty range, connect up a known signal that would be about half scale and note...
  13. (*steve*)

    I need a voltage follower with >= 1Amp output for experiments

    Ummmmm, because there's a transistor in there perhaps. The transistors are connected as voltage followers too. Do you understand how transistors work?
  14. (*steve*)

    0 to 10v outputs in parallel

    As long as all outputs have a series diode for isolation, you should get the effect you're after. Be aware that if they're AC outputs then they cannot be diode protected!
  15. (*steve*)

    Fm receiver circuit .

    You really want to avoid this. Finding good explanations of how these receivers work is not trivial. They have complex modes of operation and you often find either extremely complex descriptions by people who *might* understand, overly simplistic descriptions by people who might *think* they...
  16. (*steve*)

    I need a voltage follower with >= 1Amp output for experiments

    Just stick a couple of transistors to the output of the op-amp. This is the basic circuit. Choose transistors which the op-amp can drive sufficiently to get the collector current you require.
  17. (*steve*)

    cheat sheets

    As unreadable as James Joyce is, your comparison with @tedstruk does poor old James a terrible disservice.
  18. (*steve*)

    I need a voltage follower with >= 1Amp output for experiments

    Then, do you just want a voltage regulator set to some sufficiently low voltage? I think you're going to have to describe what it is you want to do rather than concentrate on how you think it can be done. I fear that you may have in your head that you can use this 1/17th voltage to somehow...
  19. (*steve*)

    I need a voltage follower with >= 1Amp output for experiments

    Do you want to both source and sink current?
  20. (*steve*)

    How to control the field current of an alternator by using PWM?

    Yeah, I know :-) That's still how... And so is that. But at least we can extract from your description what the "WHAT" is: You want to make an exercise bike where you can adjust the effort required to pedal it. Presumably you have the bike bits and some way to connect it to an alternator...
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