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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.

    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...
  3. 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...
  4. 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...
  5. 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...
  6. 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...
  7. 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...
  8. sureshot

    You tube channels.

    Quit liking you tube tutorials and similar. Can anyone suggest some good author hosts ! For the moment I have exhausted all of Dave Jones videos on the eevblog. Any other channel suggestions appreciated, thanks for reading.
  9. sureshot

    Wanted: Very large heatsink.

    Wanted very large heatsink capable of accommodating 6 x TO3 transistor packages. Drilled or undrilled is fine.
  10. sureshot

    Isolation washers.

    Just a general question, with the grey silicone isolation washers, would you use them dry, or with thermal compound ? I know with mica washers you should use thermal compound. But watching Dave Jones on the eevblog on his adjustable current source he made, the power devise was mounted dry, but...
  11. sureshot

    Substitute transistor.

    Having a look for another decent psu circuit i found this in the image below. Problem is i am having problems finding a BD131 NPN transistor. I was wandering if anyone can help with a substitute, thanks for reading, any help appreciated. Having a few ideas like the BD437 but not completely sure.
  12. sureshot

    Solder issue.

    Doing a bit of soldering today, usually I use lead free 4% silver 95.5 % tin 0.5 % copper. All's going well. Then to reinforce some traces I used some 60 /40 lead tin solder I had spare, as the high grade silver solder is expensive. Anyway I went back to components soldering, and was getting...
  13. sureshot

    Over voltage protection.

    A quick question here.. How affective in terms of speed, and function is a fuse and zener diode protection against over voltage. This compared to adding an SCR and it then being a crow bar circuit. So my question is, will a fuse and zener be suitable for psu circuit over voltage protection ...
  14. sureshot

    Transistor hfe

    Recently i've built a couple of voltage regulator transistor emitter follower circuits, using a single TIP2955, and two TIP2955 transistors. Curiosity has led me to a more powerful transistor. At this stage i am unsure as its gain minimum is quoted at 1K or 1000mA, its power rating is a lot...
  15. sureshot

    Resistor values.

    After trying a 12 volts power supply circuit with a single TIP2955 transistor as a pass element, and a 78S12CV voltage regulator this works really well. This is the schematic with the single transistor. I would like the try and build a 10 Amp version with two of the same transistors. I think...
  16. sureshot

    LM317 question.

    Merry Christmas to the Community, hope every one is enjoying the holidays. Just a quick general question on the popular LM317 voltage regulator. For better precision, can you use 0.25 watt +/- 1% metal film resistors for R1 and R2 or do they have to be 0.5 watts, which I can only get in +/- 5%...
  17. sureshot

    Pwm of regulated output.

    I've never tried this, so just some advise if anyone can help. Can I pwm a smps using a pwm unit to control the smps voltage for DC motor control. All is 12 volts. Smps is a converted server psu, the pwm unit has a 2.5 - 35 volt input, load on the modual is 6.5 Amps maximum. Would the pwm unit...
  18. sureshot

    Converted atx psu whistle

    Wander if anyone can throw some light on a converted atx PSU issue. OK so I followed the normal route and loaded the 5 volts rail with 10 ohms 10 watts resistor to use the 12 volts output, only there is an audible whistle, whilst it does not affect my use of the unit it is annoying, I have found...
  19. sureshot

    Resistance heater.

    Looking for some help if possible to building a resistance heater. Would i be right in thinking that four 12 ohm resistors in parallel will give me 3 ohms and with 12 volts an output power heater of 200 watts if my four resistors are 50 watts each. Any help appreciated, my issue is thinking my...
  20. sureshot

    Voltage tolerance.

    Just a question on the LM317 and its relatives. Can anyone tell me if 0.25 watt 1% resistors can be used instead of 0.5 watt resistors of 5% tolerance. Many thanks for any help. :)
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