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  1. TCSC47

    Simple SW receiver on 3V?

    I presume you are thinking 9V means you will use a PP9 which have a reputation for not lasting. However a modern alkaline PP9 can last quite well, particularly if your radio uses headphones instead of a power amp and speaker. Alternatively you can buy rechargeable PP9 style batteries but they...
  2. TCSC47

    PSU Silverstone ET550-G dead after thunderstorm (turned itself off)

    I think you have gone as far as is practical with such a fault. You have shown it is not a blown fuse and that the rectifier seems ok. Without a circuit diagram and more knowledge than we can supply simply here I would seriously suggest you bite the bullet and buy a new PSU. Two things would...
  3. TCSC47

    Adjustable current souce 12Vin 400mA o/p 32W

    Many people are happy to design powers supplies thinking they are very simple. On the surface, they are but in reality there are many little pitfalls. I always remember trying to discuss secondary breakdown characteristics of a particular power transistor with an application engineer from the...
  4. TCSC47

    Need a simple adjustable device to lower signal voltage?

    A cautionary story. When I was training to be an electronic engineer way back in the late 60's, I came across the design rules for a small 12V to EHT inverter. I immediately adapted it to try and use it as an electronic ignition device for my car. I produced the 50KV needed for the spark plugs...
  5. TCSC47

    27Mhz FM Transmitter and receiver circuit.

    I assume that you have googled the subject. There are a few circuits out there but not many. There is a reason for this. CB radio was introduced in the 70's to give untrained people access to the sort of communication that radio amateurs have. But if any Tom, Dick, or Harry has access to DIY...
  6. TCSC47

    Hi Everybody

    Thanks, HK.
  7. TCSC47

    Hi Everybody

    Hi everybody I've been a member of this forum for almost a year now, but I haven't done much posting. I am retired now after a varied career as electronics engineer and then a teacher and lecturer. My qualifications range across electrical and electronic engineering, physics, and environmental...
  8. TCSC47

    Where can I learn how to design a transformer?

    I simply specified input and output voltage and output current with 10% or so extra. Also the frequency of operation. I also had to specify the type of construction, E&I lamination or toroidal if I had to minimise magnetic leakage. And things like what sort of encapsulation, if any, and any...
  9. TCSC47

    24Vac, 24Vdc or 12Vdc universal input interface to 3.3V microcontroller

    My advice. If this is a self educational project, then go for it. But if this is for a commercial manufacture, then I would suggest using proprietary power supplies produced in large numbers by a specialist manufacturer with all the problems ironed out. Psu design looks quite simple on the...
  10. TCSC47

    Fluorescent Lamp/Ballast/Starter Help

    I'm afraid I've run out of thoughts. Maybe faulty tube or ballast?
  11. TCSC47

    relay sticking

    I beg to differ. It is possibly the arcing that causes the welding of the contacts. It is not the water displacement properties of WD40 we are using here but the electrical insulating properties of the WD40 just before the contacts make or break which will stop the arcing. However when the...
  12. TCSC47

    Fluorescent Lamp/Ballast/Starter Help

    The tube shown in the picture of your set up is a CFL (compact fluorescent lamp) and may already have a starter and ballast inductor of some sort incorporated into it. If so, your circuit is not going to work. See https://en.wikipedia.org/wiki/Compact_fluorescent_lamp Re Duke37 comment...
  13. TCSC47

    Where can I learn how to design a transformer?

    I presume you mean a power transformer. I've got a very old book, Coil Design and Construction Manual, Bernards Radio Manual No 160, dates from 1960 (!) but power transformers have not changed much, if any, which I once used to design and construct a transformer. Guess who the editor was ---...
  14. TCSC47

    Variable Frequency Op-Amp Astable

    XP, you have chosen an excellent circuit to produce a square wave out. The next step is to knock it up on a prototype board and experiment with it and see that the equations given in the article you reference, actually work. (They will by the way.) You will need access to an oscilloscope to view...
  15. TCSC47

    relay sticking

    An emergency repair, if you have access to the relay contacts, would be to spray the contacts with a maintenance spray such as WD40. Such a repair could last 6 months to a year. There are commercial fluids specially concocted to do the job but we all have a can of WD40 somewhere near at hand...
  16. TCSC47

    Restoring a FOXX FUZZ-WAH

    Glad you are enjoying the project tedstruk. Rock On!
  17. TCSC47

    Help with simple circuit; wireless torch

    If you are finding this electronics interesting and want to pursue it further, a use for an oscilloscope has already been mentioned. There are lots of 2nd hand ones for sale for less than £100 or so, and you don't need anything but a very basic one. Before that you would need a reasonably good...
  18. TCSC47

    Temperature sensor

    Could you give component numbers for the temperature sensors and the cct diag of the temperature control circuit?
  19. TCSC47

    MQ 135 sensor

    But looking at the costs of commercial gas detecting systems there would appear to be a lot of money to be made if you can design them. Calibration is a problem. I intoxicated myself when attempting to measure how much my detectors responded to toluene (glue sniffing)! On another occasion my...
  20. TCSC47

    MQ 135 sensor

    Using gas sensors like the MQ135 is something I dabbled with for a guy who wanted to differentiate gasses, way back in the early 80's. We couldn't make it work because as HK says, you can not do it. I am not up to speed on modern gas sensors but here is a page that looks interesting...
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