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  1. sureshot

    Darlington transistor hfe.

    I ended up using 90000uf of capacitance and a low drop out regulator do avoid to much voltage drop underload.
  2. sureshot

    Darlington transistor hfe.

    Yes thank you, indeed i posted the schematic after Steve made his suggestion, not knowing what i was using as a circuit. I did note these resistors in the MJ11015 data sheet, the description explained it. Thanks for the reply. I'm just playing about with a few different transistors at the...
  3. sureshot

    I'm getting there, slowly

    Very cool, looks like we have similar interests. Nice size and reuse of the atx cases.
  4. sureshot

    Darlington transistor hfe.

    Having had time to think it over, and looking at your NPN suggestion, its looks like the first transistor could be lower rating. As the current passes from emitter to collector, the final transistor is doing all the work. I noted the TIP31 was rated for a maximum collector current rating of 3...
  5. sureshot

    Darlington transistor hfe.

    Thanks for the reply Steve. Yes stability is the reason i wandered if a pair of TIP36C transistors is to high in hfe of a final darlington pair. The circuit is the simple boost linear regulator current circuit. I know its a simple circuit, I've done it with a single MJ11015 power transistor...
  6. sureshot

    Darlington transistor hfe.

    Looking for some advice on transistor hfe of bipolar juction transistors. I have some TIP36C transistors and wanted to pair two as a darlington pair. The application would be as a linear voltage regulator pass transistor. I have built circuits with a single darlington package in the past, that...
  7. sureshot

    Looking for a high current darlington transistor.

    Thanks Steve, i'm slowly getting my head round transistor specs.
  8. sureshot

    Looking for a high current darlington transistor.

    Thank you for the link, i didn't think just darlington transistor as a search term was enough to narrow down a high current component. I will give it a go, thanks.
  9. sureshot

    Looking for a high current darlington transistor.

    Thanks Bob, it would be for linear pass transistor use, not a switch sinario. A look around the Web only threw up one article I could find, link below. So I guess BJT's are better in this application. I might try the mosfet circuit in the link, I'm curious to see how it behaves...
  10. sureshot

    Looking for a high current darlington transistor.

    Thanks for your replys, yes I knew about the two transistor darlington, but prefer a single component solution. It's for mounting 4 x transistors to a 100 watt cpu heatsink with fan. As a project for mounting and potting to a single large heatsink, then potting it, as it's outside of the case...
  11. sureshot

    Looking for a high current darlington transistor.

    Basically as the title says, does anyone know of a high gain hfe high collector current pnp transistor. I'm looking for a flat style package like the T03P case. The best i can find is a TIP147, I was hoping to find a transistor like above with a hfe between 750 and 1000 preferably a darlington...
  12. sureshot

    Buying components from China.

    That's the capacitor picture I've seen before, this is a taste it and see thing really. I've no previous of international buying, be really good if it works out. Its a fraction of UK prices. Thank you for all your replays, much appreciated.
  13. sureshot

    Buying components from China.

    Thank you for your replys, and links. It looks promising then, in my case I've used eBay, but its still from the far east. I was just a bit dubious as you see TO3 transistor packages with nothing in them, also lower uf capacitors stuffed in a larger uf can. Just things I've seen others get...
  14. sureshot

    Buying components from China.

    Hi all ! Been a while since i was last here, trying to get some small projects going...... Here in the UK components cost a fare bit, even more so with vat at 20%. I've ordered a few semiconductors, does any one else buy much from the far east with any luck ? more on quality than any thing else...
  15. sureshot

    Converted server psu's

    I will have a look round these suppliers, thanks Harald.
  16. sureshot

    Converted server psu's

    Thanks Harald for your help, I will give this company a call and see how much one of these emi filters would be. Thanks again for the link.
  17. sureshot

    Converted server psu's

    I have a bit of a hobby going on converting old server power supplys, my use of these is mainly for cb radio. What I've noted with a few is electrical noise when connected up to the radio, some units are fine and are clean enough on there output for use, others are just to noisy. An example is...
  18. sureshot

    Hook Up Wire for PSU

    Yes I did mean insulation, dam auto correct spelling lol. Retail wire and cable in almost any application should be more than adequate, having the correct cat and rating goes with out saying.
  19. sureshot

    Hook Up Wire for PSU

    Military and aviation grade cable and wire would probably have a more pure grade conductor, less inpurities in the wire. And the installation would also be superior In many high grade cable and wire. Having said that, very good quality cable and wire is avaliable for the retail market, and...
  20. sureshot

    Zener diode as volt dropping resistor??

    Intersting, what do you plan to power with 75 - 90 Volts, where 110 Volts can't be used ?
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