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  1. Hero999

    random number by led one digit

    The 74HC00 is the same price as the 555, uses less power and the oscillator circuit uses the same number of components as the 555.
  2. Hero999

    coin toss electronics by ic ne555-cd4017

    The 74HC74 is available in the same size DIL package as the old CD4013.
  3. Hero999

    coin toss electronics by ic ne555-cd4017

    Why post another circuit which basically does the same thing? You don't even need a 555, it's possible to do this with a single CD4013 with one half configured as an astable. I prefer to use the modern 74HC74 though as it can drive LEDs brightly and run off a couple of AA cells.
  4. Hero999

    random number by led one digit

    The image is too small to see. The full size original can be found on the site it was copied from. That site contains nothing but schematics taken from other websites: what's the point? I assume you have the permission from the authors. Design your own circuits or at least make improvements...
  5. Hero999

    HELP

    Please start a new thread and post in English, if you want help.
  6. Hero999

    Voltage Doppler for 6v lead acid battery

    What's a voltage doppler? No enough information, piezoelectric materials have 100s of applications.
  7. Hero999

    [ARTICLE] Build your own UV exposure box

    According to the picture, the F15T8 is not listed  so is not suitable for the tube you've linked to.
  8. Hero999

    Electronic Welder 200A

    Try replacing the 10R resistor. I asked for a PNG not to be difficult but because JPEG is a lossy format. Just saving a JPEG in PNG format doesn't give a better image because the information has already been lost when the picture was previously saved as a JPEG. In this case you all you did was...
  9. Hero999

    Electronic Welder 200A

    Can you please post a better schematic? At least in PNG format, that way I may have  some chance of being able to increase the contrast so it's readable, the JPG just goes fuzzy when I increase the contrast. How did you measure the voltage? You do know it's a high frequency transformer so you...
  10. Hero999

    Solar charging a small SLA

    What's the voltage of the solar panels when no load is connected? It's generally much higher than 12V, mine are >17V. An LM317 will only drop a couple of volts so won't cost you much. The only thing is the leakage current may be too high as when it's dark the batteries will discharge via R1...
  11. Hero999

    220v dc motor speed control using a microcontroller (PWM)

    The 4N25 has a maximum voltage rating of 60V and a current rating of just 50mA so is unsuitable for driving the motor directly. You haven't provided enough information. How much current does the motor use? Where are you getting the 220VDC from? Is it a smooth supply such as a battery or an...
  12. Hero999

    Need help for project. 12v Regulator

    Why were you even considering putting three regulators in series? The output current would remain the same but the drop-out voltage would triple. Assuming the encoder will be damaged by 17V (it might be able to work of that voltage fine) you need a low drop-out regulator, otherwise the battey...
  13. Hero999

    Transistor OverHeaating

    Post a schematic. What's the: Base current? W/oC rating of the heat sink? Switching frequency? And is the load inductive?
  14. Hero999

    [SOLVED] Dropout voltage concerns.

    The solution is just to power everything differently off the battery. I don't see what all the fuss is about, you've got a range of appliances which either have built-in voltage regulators (this applies to the answer machine, router and modem) or are designed to run off a wide range of voltages...
  15. Hero999

    Some brain draining needed, thanks

    The TRIAC will now turn on but you've stlll not paid any attention to the issues raised in my previous posts.
  16. Hero999

    12v adapter and 12 v 7 ah battery to be charged

    With a 12V battery and a linear regulator, you're wasting over half of the power. You could use a low dropout regulator and a 6V 7Ah battery which is half the size and it will power the circuit for just as long. What's the point of the diode? To stop the battery from injecting power back into...
  17. Hero999

    Signal voltage adjustment problem

    You don't need to ground the 0V rail.
  18. Hero999

    Solar charging a small SLA

    Yes, gassing is a problem for lead acid batteries connected to solar cells, even 100mA can cause a 3.2Ah battery to gas. In fact I've had problems with a 14Ah battery gassing when being fed with 50mA continuously. The problem is the voltage. Are you planning to leave the solar cells connected...
  19. Hero999

    How to do a sea border detector?

    What do you want help with? And don't say everything. No one has responded because you've not shown what you've already done. I admit I don't know much about GPS. What's your budget?
  20. Hero999

    automated variac 0-220Vac

    Such a solution will require more expensive electronics, be less tolerant of voltage transients and less efficient. I don't think you've thought it through. For a start, you'll need a class D amplfiier otherwise the efficiency will be abysmal. I suggest you do more research.
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