Search results

Search Forums New Posts
  1. (*steve*)

    78L33 regulator

    Are you *really* applying AC to the input of a DC regulator? That's a baaaad thing m'kay. At the very least you need a diode in series if you're after a string of 3.3V pulsed at line frequency.
  2. (*steve*)

    One switch to rule them all

    A switch with multiple poles can be used. This means the DC and AC can be kept separated.
  3. (*steve*)

    Help Identifying a Battery

    A colleague of mine brought a couple of tiny remote control cars for "show and tell" a couple of years ago. They charged in a second or so and ran for a respectable time. They used supercaps. At the time, supercaps were pretty exotic and I was surprised to see them. Maybe this is the answer?
  4. (*steve*)

    Question about PTC fuses

    Thanks, Thanks, I I will will try try not not to to double double post post :-) :-) With these PTCs you need to look at the specs. I would be surprised if two 24V 500mA polyfuses were dramatically different in size. But I've been surprised before. If you know they're rated for a particular...
  5. (*steve*)

    Question about PTC fuses

    These are not fuses as such, but a form of thermistor. Rather than go open to stop current flowing, they rely on self heating to cause their resistance to increase. Rather than a very gradual increase in resistance these devices exhibit a fairly abrupt change in resistance. Devices are chosen...
  6. (*steve*)

    Playing with valves

    It is certainly a learning experience. When I report things like the snr and THD to my musician colleague he encourages me with the explanation that these are expected or even desired.
  7. (*steve*)

    Playing with valves

    Some more measurements last night. With a 25mV (RMS) input, the THD is around 0.6% with a SNR of about 65dB. The THD remains almost constant to 100mV input. At 175mV the THD rises to 2.5%, 250mV it's 5.5%, and at 500mV it is 11%. Measurements were almost constant from 200Hz to 10kHz...
  8. (*steve*)

    ForkLift Gokart

    Yeah, well that's critical information, so it would be best to find out.
  9. (*steve*)

    ForkLift Gokart

    You need to find out what sort of motor it is. It is unlikely to be BLDC if it turns when you connect 12V to it.
  10. (*steve*)

    high DC voltage reducer

    In any case, it's still way safer than a linear regulator running from the rectified power line. I will agree that a "good" usb charger is worth it's weight in defibrillators (or something). These days it's getting harder and harder to define "good" in a way that is useful :-(
  11. (*steve*)

    high DC voltage reducer

    In retrospect I should have assumed they were delta voltages. My fault :)
  12. (*steve*)

    high DC voltage reducer

    Ok, you should be fine. I had not assumed they were delta voltages. Perhaps I missed something earlier.
  13. (*steve*)

    high DC voltage reducer

    Run it between two phases (as long as the voltage is ok for the adapter) Assuming you don't know how to calculate this... Its 270VAC. But that raises the question of how you got 150VDC. Are you measuring 135VAC between the phases or between the phase and the neutral you don't have?
  14. (*steve*)

    high DC voltage reducer

    Get a usb charger designed for "universal" input (generally 90 to 265VAC) and use that. If you user a linear regulator you will need to dissipate about 65W of heat. If you have no room for a transformer then you won't have room for the massive heatsink either.
  15. (*steve*)

    high DC voltage reducer

    Use a transformer.
  16. (*steve*)

    DC Motor drive

    Or put the diac inside a diode bridge.
  17. (*steve*)

    Single led vumeter using LM311 comparator at the output amplifier?

    But surely if you don't like an answer you should keep asking people until you get an answer you like? :-o
  18. (*steve*)

    Wi-fi

    No, that's something else entirely.
  19. (*steve*)

    Wi-fi

    If you're getting it from eBay it might be worth looking at a small yagi or a panel antenna. Just make sure you get the right connector. It's not a huge deal if you don't, often an adapter can be purchased for a little more than $1, but the time it takes to get them is bloody annoying. My...
  20. (*steve*)

    Playing with valves

    The cut and paste isn't the issue, its the recording of all the raw data and entering it into excel.
Top