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Posts posted by Uman

  1. I have a couple of questions about PCB software and manufacturers.
    I am in the market for a PCB design and layout application software to produce small single and double sided boards. There are so many to choose from and trial versions to "learn", I am having trouble selecting. Of course price is a factor and so is ease of use and the learning curve. I will not use this daily, so I would like an intuitive progam. I experimented with PCBexpress PCB software V2 freeware and it seems good. If anybody has experience with PCB Express customer satisfacation, I would be interested too.

    Also, can you recommend a good prototype PCB company to produce a couple of prototype boards at good quality and price?

    Thank you,
    Jeff in Florida

  2. My class project is to build a battery operated light detector circuit using a photodiode and a LED light bar to register the light intensity. The photo diode output is connected to a single-supply 5 volt Op Amp (battery operated). The Op Amp feeds a national semi LM3914 IC light bar driver, which powers the lightbars.
    When the photodiode detects light, the light bars illuminate according to the light intensity; and works fine. Unfortunetly, I need the reverse; I need the light bars to illuminate when the photodiode is in the dark and extingush when the photodiode detects light. What can I put between the Op Amp out put and the lightbar driver to inverse the driver signal? The OP Amp is battery operated and is powered by +5v, so inverting the Op amp connection will not work.
    The LM3914 LED lightbar driver input single is 0 to 2.5vdc for full off or full on respectfully.

    Any help or discussion would be a big help.
    Thanks all.

  3. I am designing a circuit that is powered by 6 AA batteries (9 volts). Due to the circuit load, there is a concerned about the power draw on the batteries. How do I calculate the the circuit continous run time until the battery voltage drops below 7 volts. The circuit will draw about 100ma when energized.
    Thanks for any help,
    Jeff in Florida

  4. Hey Audioguru
    Thanks for your help and everyone else too. I ordered the CD4060 oscillator/counter chip from Fairchild semi and will try to integrate it into the circuit and make it work. Sorry about my confusion on the 4060, I ment to ask about the 2240 chip with the 555 timer you mentioned. How is it different than the 4060? It is an oscillator/counter right?

    Thanks again,
    Jeff in Florida

  5. Hey audioguru,
    I am very interested your proposed circuit. What is a "4060"? I search Fairchild and could not locate the data sheet. Please help.


    I would like the shut off circuit to reset its timer and start over, if a signal goes high from a second circuit (feed back). If no signal is detected, than the shut off circuit would power off the circuit after a predetermined time.

    Is this possible? My mulitmeter powers off if no signal is detected for 10 minutes.

    Jeff in Florida

  6. I am designing a circuit that detects the presents of an object using an IR emiter and transistor detector. The circuit is powered by a 9v battery and sounds a buzzer when the IR light beam is interrupted.
    I would like to add a feature to auto OFF the circuit when no objects interupt the IR beam within 60 minutes, to conserve batteries in the event I forget to switch it off. The power switch will be cycled to activate the circuit again.

    I suspect a 555 timer circuit embedded in the above circuit is part of the solution. Is the 555 timer the way to go or is there a better way?
    what would this circuit look like?

    Is it possible for the circuit to automatically reset the 60 minute timer after each interrupted event and power down after 60 minutes of inactivity?

    Thanks for you help,
    Jeff in Florida

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