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  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Recent content by Nigel Goodwin

  1. Nigel Goodwin

    PWM replacement for car lighting dimmer

    Q3 is upside down as well, collector and emitter are swapped!. The emitter resistors are also far too high at 10K, and not really needed at all. In fact the whole drive stage is wrong, and won't work - I'm on holiday in Scotland at the moment, otherwise I'd post the driver circuit I use - I'll...
  2. Nigel Goodwin

    Excel Bug?

    I never rely on precedence, as it's often controversial, so I always add brackets to ensure it does the maths the way I want :D This is mainly in programming languages, as I rarely use Excel.
  3. Nigel Goodwin

    Excel Bug?

    As I've already said, the formulas are completely different, I'm quite bemused why you would even try different versions?. The reason they both work with 3000 is that the result of the initial subtraction is 0, so the first part doesn't do anything. Computer maths tends to be non-integer, so...
  4. Nigel Goodwin

    PWM replacement for car lighting dimmer

    A quick further comment, where's the current limiting resistor for the LED, and what's with D4?, wrong way round?, and connected to the wrong place?. Also adding some hysteresis around the comparator, a decent opamp, and wiring it properly,would be good ideas (it's not currently monitoring...
  5. Nigel Goodwin

    Excel Bug?

    As I see it, the formulas are clearly completely different, the second has an extra '^2' applied to (A4-3000), the first one doesn't. There's also a considerable amount of controversy about rules of precedence, best to use brackets to remove any such concerns. But mostly, is the extra '^2'...
  6. Nigel Goodwin

    Existing old type LM324 based automatic voltage stabilizer circuit evaluation

    There appears to be no mention of Q1, Q2, Q3 and associated circuitry in your simulation file?, never mind the required settings for their pots. That is the functional part of the design, without those (and correctly setting the pots) it won't work, as there's nothing to work.
  7. Nigel Goodwin

    Existing old type LM324 based automatic voltage stabilizer circuit evaluation

    Yes, D1 in your simulation, it's the wrong way round - both the opamp comparators, and Q1, Q2 and Q3 are entirely dependent on the settings of the potentiometer, so it depends where you set the pots to. It would be helpful to you if you had the setting up instructions for the pots. I can't help...
  8. Nigel Goodwin

    Existing old type LM324 based automatic voltage stabilizer circuit evaluation

    You appear to have D1 the wrong way round in your diagram?, the original diagram was correct. There is no 'gain' as such in the opamps, they are wired as comparators - it's a basic window comparator. The opamps have no functional part in the circuit as such, that is all done crudely by Q1, Q2...
  9. Nigel Goodwin

    Aiwa Z-R700 music hifi has dim lighting and none of the systems work when powered up

    As it worked before you replaced the belts, it's pretty likely that you've disturbed something, or connected something to the wrong place, it's unlikely to be an actual 'fault'. A simple google finds the service manual...
  10. Nigel Goodwin

    Wow – Do You See The Problem?

    I don't see anything 'weird' at all, there's rarely any need for polarisation in mains leads, all UK mains plugs are polarised, earthed, fused, and MANY of them are on the end of leads that aren't polarised, often the same figure 8 lead as in the picture.
  11. Nigel Goodwin

    headphone amplifier with microphone input

    The only 'adjustment' required is where you set the volume control.
  12. Nigel Goodwin

    headphone amplifier with microphone input

    The Velleman kit is probably all you need, just for feeding headphones you don't really need a power amp, many opamps are plenty loud enough for headphones. One of our products at work uses headphones, I use a bridged TL072 opamp to feed them, and actually have a 100 ohm resistor in each...
  13. Nigel Goodwin

    Vero board cutting

    Sharp knife and a steel ruler, or just a small hacksaw
  14. Nigel Goodwin

    using a RTC in SF basic

    I'm sure we're all looking forward to hearing, and seeing, how you get on :D
  15. Nigel Goodwin

    Home Smoke detectors are all Beeping Batteries are not dead.???

    Why didn't you dump it 4 months ago?.
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