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  1. Arouse1973

    Sensor interface, OP AMP, -500mV +500 mV to 0-5 V amplifier

    You don't need to increase the value of the resistors. A potential divider won't work, you need something to track the voltage to maintain 0.5 Volts above the input. The op-amp can be a different type of course. But you need to make sure it's suitable for working with voltages close to the...
  2. Arouse1973

    Sensor interface, OP AMP, -500mV +500 mV to 0-5 V amplifier

    Here is a circuit that does what you want. It's as simple as I can make it. The signal which might need to be buffered is denoted by V2 on the circuit. V3 is an offset voltage which you will need to generate. The signal +V3 is amplified by 10 and then divided by 2 at the output. Thanks Adam
  3. Arouse1973

    Sensor interface, OP AMP, -500mV +500 mV to 0-5 V amplifier

    Leave it with me and I'll see if I can sort something out for you. Adam
  4. Arouse1973

    Sensor interface, OP AMP, -500mV +500 mV to 0-5 V amplifier

    So I guess with a zero volt input you are going to want 2.5 Volts out? Adam
  5. Arouse1973

    Hello

    Hi Steve, welcome to EP. Adam
  6. Arouse1973

    Sensor interface, OP AMP, -500mV +500 mV to 0-5 V amplifier

    Another question. What's the reason you need 0 Volts? Adam
  7. Arouse1973

    Sensor interface, OP AMP, -500mV +500 mV to 0-5 V amplifier

    Hi Amin So your not worried about the -500 mV then? Adam
  8. Arouse1973

    Impedance of two stage amplifier

    Um yes Dave. A 5K driving a 400 Ohm?
  9. Arouse1973

    Need help with heating element

    Here you go.
  10. Arouse1973

    Need help with heating element

    Hello Have a look at Nichrome wire first and see if this will work. Oh and welcome to EP. Adam
  11. Arouse1973

    Hi guys

    Welcome Robert. Nice to have you here. Adam
  12. Arouse1973

    RPM sensor for rotating shaft

    Ah here they are. They are Avago, I thought they were Honeywell. http://uk.rs-online.com/web/p/reflective-optical-sensors/4966443/ Adam
  13. Arouse1973

    RPM sensor for rotating shaft

    The device has an IR LED and photodiode built in. Let me see if I can find a datasheet. Adam
  14. Arouse1973

    RPM sensor for rotating shaft

    Yes I agree with M. I would go for magnetic or optic sensing. I have used a Honeywell opto reflector with a very shiny piece of tape attached to a shaft before to sense the rotational speed. Adam
  15. Arouse1973

    Voltage and current relation difference between Ohm's law and Power

    What do you mean justify? Adam
  16. Arouse1973

    Getting a led to turn on when voltage is under 3 volts on a battery

    Hello Juvoal. Have a look at a comparator. You will find lots of low voltage alarm circuits on the net. Thanks Adam
  17. Arouse1973

    Vacation

    Have a good one mate! Adam
  18. Arouse1973

    Cup with heat awareness

    You might not need the constant current circuit I mentioned if you use the USB charger you posted. The constant current charger is in my opinion the safest way to charge NiMh. If you set the current to C/10 you can virtually leave them connected all the time. This does have a disadvantage of...
  19. Arouse1973

    Cup with heat awareness

    Something like this? http://www.dhgate.com/product/wholesale-lot-20pcs-usb-type-a-female-to/151843394.html
  20. Arouse1973

    Cup with heat awareness

    I think you are going to have to get an adaptor lead which has the mating connector (micro USB I think) and then use a constant current charging circuit for the NiMHs. What is the capacity of the batteries you plan to use? Edit: you might be able to get a cable that connect from the wireless...
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