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  1. Hero999

    1.5V buzzer circuit

    I came up with this circuit yesterday, it's basically an h-bridge and astable multivibrator in one. I've not actually built it yet but LTSpice says it works all the way down to 0.9V, making it ideal for single cell operation. The saturation loss for both transistors ranges from 184mV to 224mV...
  2. Hero999

    USB cellphone charger

    Looks like someone needs to learn how to use Google. http://www.google.co.uk/search?client=opera&rls=en&q=USB+phone+charger&sourceid=opera&ie=utf-8&oe=utf-8
  3. Hero999

    parasitic capacitance

    Reduce the resistor values. Reduce the parasitic capacitance by making the circuit physically smaller. If it's an amplifier, there are several techniques used to reduce the Miller effect, see Wikipedia. http://en.wikipedia.org/wiki/Miller_effect#Mitigation
  4. Hero999

    USB cellphone charger

    The voltage is 5V and there is enough current to charge a battery. The standard socket for most phones is a miniature USB socket which can probably be connected to a computer to charge the phone.
  5. Hero999

    LM338 Power Suply Current Regulator

    Fight, The circuit I posted in my first reply to this thread uses several power transistors so the power dissipated by each power transistor is only around 35W. http://www.electronics-lab.com/forum/index.php?topic=20224.msg92354#msg92354 We're going round in circles.
  6. Hero999

    Cable fault locator for underground PSTN cables

    TDR is just about the only way of locating a fault in an underground cable.
  7. Hero999

    Don't cut costs on wall warts...

    Don't throw it away, simply glue them together or remove the SMPS from the wall wart for use inside a project's case. Yes I agree, this is bad diesign and I was going to sat that it wouldn't happen in the UK because our plugs have insulators near the base of the prongs, then I realised that...
  8. Hero999

    Evaluating total energy usage from just DC voltage and current

    +/-10mV over waht voltage range? If you're talking about 190V then that' not easy because it'sn early 0.005%. If you're talking about the 50mV read from a shunt, it's 20% which is poor. Are you talking about 10mV of offset and if so, over what voltage range? Here's a circuit which...
  9. Hero999

    Evaluating total energy usage from just DC voltage and current

  10. Hero999

    Evaluating total energy usage from just DC voltage and current

    As I said above you'll get this problem with a sense resistor because the differential op-amp used to measure the voltage across it will still have some offset, especially if you keep the voltage low to save power. You need to measure the offset and cancel it using software, which isn't hard.
  11. Hero999

    LM338 Power Suply Current Regulator

    I explained how the regulator works on Silicon Tronics which you can't access so I've coppied and pasted the text. The circuit compriese of two parts: the rectifer/voltage doubler and the actual regulator iteslf. Rectifier This part of the circuit converts the 15VAC from the transformer to...
  12. Hero999

    LM338 Power Suply Current Regulator

    What version of Internet Explorer do you use? It works for me in IE 8. There is some Internet censorship in Pakistan but it's not as bad as some countries. http://en.wikipedia.org/wiki/Internet_censorship_in_Pakistan The statements you made a couple of posts ago are true. I've attached the...
  13. Hero999

    Simple Rack is offering a Summer Blow out sale.

    There's no point in having a poll with all the answers the same. Anyway, I vote for GTFO and stop spamming. The purpose of this section is for fellow hobbyists to sell parts, assembly and test equipment to each other, not for companies to sell their rubbish.
  14. Hero999

    LM338 Power Suply Current Regulator

    It isn't my site but Dazza's (another member of Electronics Lab), I just help to run it for him. It works for me, there must be something wrong with your Internet connection, try again later. There's no circuit diagram attached to post 23. Those aren't questions, they're statements. You need...
  15. Hero999

    LM338 Power Suply Current Regulator

    Audioguru answered your question. If I don't respond it's normally for any of the following reasons. I'm busy You haven't made it clear you're asking a question, respond clarifying it and add more information, if you can. I don't think you've given the question enough thought and feel that...
  16. Hero999

    Evaluating total energy usage from just DC voltage and current

    It should be fairly simple. Measure the transducer's output when there's no current flowing and subtract that value from the current measurements taken. How much does it drift? If it's significant you'll have to null at regular intervals. If drift isn't a problem then you should be able to...
  17. Hero999

    Evaluating total energy usage from just DC voltage and current

    Can't you just null the offset?
  18. Hero999

    Analog to digital signal conditioning

    The ADC will always be as accurate as the voltage you want to measure divided by 4096. Dividing, amplifying and level shifting will always introduce more error which will depend on the quality of the components used.
  19. Hero999

    LM338 Power Suply Current Regulator

    The LM338 has a drop out voltage of 3V at full current and when configured as a current regulator, the voltage reference of 1.25V across the current sense resistor, adds to it making 4.25V.
  20. Hero999

    Simple sensor project?

    I found out the name of the IC: HT2844. http://www.selectronic.fr/includes_selectronic/pdf/Holtek/HT2844.pdf There's also a chip on board which is a pre-made circuit board with the IC already embedded under a blob of epoxy. http://kitsrus.com/projects/sg10m.pdf As you want six noises, you'll...
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