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  1. (*steve*)

    Need help cross referencing this part.

    It may be easier to replace the power supply. Typically they supply 12V and 5V to the CD-ROM and not much else. The are plenty of small power supplies available that can do this. They are likely to be not much different in cost to the part you need, and you have no guarantee that it is just...
  2. (*steve*)

    Is this schematic correct?

    OK, you've made a wiring error. The resistance from collector to +5V should be constant and much lower. Check that you know which terminal the collector is. (It's the one without the arrow) Also check that C4 is 47nF, not 47uF
  3. (*steve*)

    audio transistor schema...

    What are you smoking? Your posts don't make any sense.
  4. (*steve*)

    Is this schematic correct?

    Not that I'm aware of. Where did you get this circuit from? How confident are you that it works and is reasonably well designed? Your measurements of voltage are inconsistent.
  5. (*steve*)

    Is this schematic correct?

    With the power off, measure the resistance between the collector and the +5V input. Then measure the resistance between the collector and ground.
  6. (*steve*)

    Microcontroller debugging

    By removing the debug program?
  7. (*steve*)

    Power output from a mobile phone aux socket

    Calling a speaker (or sound system) "audiophile" is like calling a car a "petrol head". Both of these are adjectives that apply generally to people who appreciate them, not that which is appreciated.
  8. (*steve*)

    Onboard charger repair. Value of ZD?

    Given @Bigrockk's zener issue (which I feel was probably caused by failure of the fan) I would recommend you replace the zener with a 2W device. It will save you if the fan in your unit ever fails (or the fan is disconnected). If there is space, mount the zener with some clearance off the...
  9. (*steve*)

    surplus analog parts

    They become far less valuable once you have tipped then in a bucket. Your options range from trying to sell them 1 by 1 to selling everything as one lot. If you don't know what you have, I'd suggest selling them bin by bin ( on eBay). You'd need a good picture of the content and a rough qty...
  10. (*steve*)

    Capacitor Protection Boards- How do they work?

    Doubtful, and I'd like to see how it's done on the other board. There's no point reinventing the wheel.
  11. (*steve*)

    Hii Everybody

    g'day
  12. (*steve*)

    How would make a smelly flatulence (fart) remover for a person with colostomy bag?

    Yeah, but I don't think I'd want the risk of an exploding colostomy bag. If the anything which absorbs or catalytically changes methane? There's a lot to be said for a closed system. However, we are talking about a medical device and as such safety is a huge thing. I'm not sure this is the...
  13. (*steve*)

    dissipation in a zener diode

    I think the reason is to limit the max voltage so as not to exceed the input voltage limit of some downstream device. In this case, the low current at the zener voltage is a good thing. Connecting a buck or boost dc-dc converter to a source like a solar panel can lead to a situation where the...
  14. (*steve*)

    Scope

    Some scopes I have that we once very expensive have selectable input impedance. The schematic shows that the 50Ω impedance is produced by simply switching a 50Ω resistor across the input. Chris' suggestion above is perfectly acceptable. Be aware that 50Ω inputs can be easily damaged by even...
  15. (*steve*)

    Capacitor Protection Boards- How do they work?

    You'll have to get me much better photos of those boards if you want me yr try to reverse engineer them. And why don't you give it a try? Your first effort was pretty good and helped me finish it off. If that is a LED and a diode directly across the capacitor then it's really not a good way...
  16. (*steve*)

    Another one Tek 2235 power supply problem

    A quick Google for the problem you're having suggests it is caused by an overloaded power supply. One of the sides may have failed, but the problem is more likely downstream of them.
  17. (*steve*)

    Another one Tek 2235 power supply problem

    I just googled for "Tek 2235 service manual". The first hit took me here: http://www.tek.com/manual/2235-service-manual Searching for CR960 in this document took me first to an explanation of the part of the circuit, and next to a parts list which have a description of the part and the...
  18. (*steve*)

    Another one Tek 2235 power supply problem

    Sorry, I misread that as a question about the capacitors. Have you tried what I suggested in post 7 of this thread? If you had problems, at which step? If you can provide a link to the service manual I can see if there is anything special about the diodes.
  19. (*steve*)

    Low Voltage Cut Off For Grid Charger

    I would recommend an FQP6N40C. In this application you need to consider the SOA of the MOSFET which is operating in the linear region. I would recommend a 5°C/W heatsink. Beware that unless you use insulating washers and mounting hardware the heatsink will have a dangerous voltage on it near...
  20. (*steve*)

    Simple current sensing (boolean output)

    You can also use a flux gate magnetometer. It's another way to detect the magnetic field around a conductor. Yes you have to expose one power wire. It doesn't seem like there is any special reason to use something exotic in this application
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