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  1. sureshot

    Why was my thread tampered with ?

    Asking for general help... See the centre of the image posted ! I can only imagine a moderator did this to it. N/A...... Two many chefs and not enough cooks, you know the old saying. Long standing members will see what I'm on about. All the best fellow electronic hobbyists.
  2. sureshot

    Inrush current smps.

    Thanks all for the help.
  3. sureshot

    Inrush current smps.

    Yes it's a real smps, it was a surplus to requirements dell power brick, picture below. I thought I'd have a go at converting it for cb radio use. For that it works fine with an 80 channel radio and a 35 watt amplifier. I was just wandering if it could supply a larger amplifier with current. Say...
  4. sureshot

    Inrush current smps.

    Thank you for the help AK. Yes I've tried adding a second lamp whilst the first lamp is already on. That trips the psu off. I've also tried two lamps from cold and connected, it won't power on from a loaded state with two lamps either. Testing the lamps resistance is approximately 1R0 each. So...
  5. sureshot

    Inrush current smps.

    Hello to the community. Just looking for some, what might be simple information. I have an 18 Amp 12 Volt smps, I'm not 100% certain, but have an idea of what's going on. On adding load (halogen lamps) the psu can handle a single 50 watt 12 Volt lamp. But if i add a second 50 watt lamp in...
  6. sureshot

    Current passing for regulator IC's

    I'm more than happy to comply with forum rules. I only used the term " Amplified current, because every site I've come across uses this term to explain a low or modest input power to a much higher output power by way of single or multiple pass transistors. But if its the way you term it, then sure.
  7. sureshot

    Current passing for regulator IC's

    Yes i know about a 1 Amp or there abouts should be the limit. Although i have made up heavier hook up wire for point to point wiring on breadboards before. It didn't go to bad. And the same with copper strip board. I usually solder up continuous heavy tracks, and double or even treble up wiring...
  8. sureshot

    Current passing for regulator IC's

    Thanks for your help with this. Yes i can see its quite a tall order to expect that much current from a 100mA linear regulator. If i could keep the current through a 1 Amp 7812 with a small heatsink, that would be doable on the prototype size board i plan using. Say with in 250mA if i can...
  9. sureshot

    Current passing for regulator IC's

    Thank you Steve for your reply. I can see there's no single one answer to this resistor value. Looks like many variables, dependent on transistor type, current drawn, and input voltage after rectified and filtered. I do understand what you have explained. For me its probably best if i breadboard...
  10. sureshot

    Current passing for regulator IC's

    I know any opposing is futile. I'm only saying as I've seen it mentioned in many other electronic sites. A quick Google does refer to current amplified. I would hop you wouldn't lock the thread at this point. I'm not quite there yet with a conclusion. I'm mostly a forum watcher from the side...
  11. sureshot

    Current passing for regulator IC's

    Maybe the only way is to breadboard this to see, putting a couple of multimeters in circuit to read current under load conditions. As a novice I'm not sure if i can obtain 2 Amps output current using a 78L12 and a single pnp pass transistor. I look at the current pass circuit for LM723 circuits...
  12. sureshot

    Current passing for regulator IC's

    Thanks for your reply. So it might not be possible to achieve a power output of 2 Amps with a 12L78 100mA regulator ? Just wandering if a darlington like a TIP147 would allow a better scenario for less current through the base emitter resistor. Would it be possible to increase the resistor value...
  13. sureshot

    Current passing for regulator IC's

    Thank you for getting back to me. So what value would be a good starting point, if I'm using a 78L12 100mA voltage regulator ? I don't really won't to keep burning the regulator out, where by its drawing to much current. In short I'm trying to find the math formula to get the resistor value so...
  14. sureshot

    Current passing for regulator IC's

    I think I'm getting some of it now. So its the voltage across the resistor that turns the transistor on ? So if the transistors base maximum voltage is say 5 Volts, i would won't it to switch on below that. Maybe 1 or 2 Volts to turn on the transistor for a current limit on the regulator of 50...
  15. sureshot

    Current passing for regulator IC's

    This is where I'm unsure, in the picture below that circuits current says it conducts current above 600 mA , below that value the regulator is doing the work. So i don't understand how a 12 ohm resistor could get the transistor to switch on at 50 mA I'm not saying its wrong, more that i don't...
  16. sureshot

    Current passing for regulator IC's

    Thank you for the two circuit diagrams. Iv'e got the TIP36C transistors, but would still like to pair one up with the 78L12 100mA voltage regulator. I was just looking for some help to see if i got the maths right for my current limit resistor on the regulators input. I only want it to do 80mA...
  17. sureshot

    Current passing for regulator IC's

    I was using a popular circuit that uses a pnp pass transistor to boost regulator current. a few web sites have this circuit diagram. I first saw it in a fairchild data sheet, for boosting 7812 regulator current. But that was for the L7812 1 Amp regulator, and not the 7812 100mA version of this...
  18. sureshot

    Current passing for regulator IC's

    Sorry for not including the data sheet, i have used L7812 1 Amp regulators before. And the higher current 78S12CV 2 Amp version, both as stand alone and in a circuit with a pass transistor. I wanted to try and see if i could amplify the current using the 7812 100mA version of this linear...
  19. sureshot

    Current passing for regulator IC's

    Looking for some help. I'm wanting to try and do a current pass circuit for a TS7812 L CT 100mA voltage regulator. My aim would be 2 to 3 Amps by way of a single pnp pass transistor as an emitter follower. My problem is keeping the regulators work to under 100mA and preferably around 80mA under...
  20. sureshot

    Darlington transistor hfe.

    Hi, the capacitance of 90000uf is filtering on the input from the bridge rectifier. Its only that large because i only had 14.70 Volts for that input. To avoid voltage drops under load. After rectification and filtering i ended up with just over 20.00 Volts. If i would have gone with less...
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