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  1. Arouse1973

    Need a 555 cct that can only be triggered once during its countdown time

    That's good, yes and a flyback diode is needed, especially as you are driving the relay from a common collector drive. The only other thing I would say is the output voltage from the 555 at 5 Volts will be further reduced due to the Vbe drops of the two transistors. You may find it difficult to...
  2. Arouse1973

    a diy security alarm design

    Absolutely disgusting behaviour if you ask me. Yes I second what John and the others have said, although we could all design you a circuit to do this, the time and cost would be greater than a ready made unit. Because you have to think about windows also. If they know you have a door alarm then...
  3. Arouse1973

    Cleaning a PCB

    That's a good idea Hop, never though of that! Adam
  4. Arouse1973

    Cleaning a PCB

    Can't beat a hugs scrubber :)
  5. Arouse1973

    Need a 555 cct that can only be triggered once during its countdown time

    That's very good, now add the other bits :) Don't copy mine, see what you come up with. Although it may be the same. It's interesting to see how other people design circuits. Adam
  6. Arouse1973

    Using pnp and npn transistor as 1 pole 2 throws switch

    You need to match the supply voltage ideally. So running from 5 volts will work. If you need a higher voltage for the load then you will have to add some more transistors that are running from the same supply as the PIC so they can switch the transistor connected to the higher voltage. Thanks Adam
  7. Arouse1973

    Cleaning a PCB

    Or big PCBs :) Ads
  8. Arouse1973

    Using pnp and npn transistor as 1 pole 2 throws switch

    It's because you have 6 Volts for your power supply and the PIC is running, I hope from 5 Volts. When the PIC pin goes to 1, there is not enough voltage to turn the transistor fully off. Thanks Adam
  9. Arouse1973

    Need a 555 cct that can only be triggered once during its countdown time

    It's good to have everyone join in, please upload a picture of yours. Thanks Adam
  10. Arouse1973

    Super long standby VOX/transponder help needed.

    Hope it works out for you. Thanks Adam
  11. Arouse1973

    Cleaning a PCB

    Again a good reply Hop. Here you go. http://www.ebay.co.uk/itm/like/171366768636?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&chn=ps&device=c&rlsatarget=&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108 Adam
  12. Arouse1973

    Help with diode.

    Can you provide a simple diagram showing the connections and polarity of the voltages, just so we are sure what you mean. Thanks Adam
  13. Arouse1973

    Need a 555 cct that can only be triggered once during its countdown time

    Hi Dave, here's my attempt if your interested. It sounds like it's similar to Lavaguava's but I don't know what package he used to design it in, might be better if he posted a picture. You may have to play around with the values for timings. Circuit works like this. When the door button is...
  14. Arouse1973

    Cleaning a PCB

    Yes this is fine for PCBs. But make sure you dont spray it on plastics, it may damage the surface. Dont use too much, just enough to clean the PCB. Use an antistatic tooth brush if you have one to loosen any dirt. Adam
  15. Arouse1973

    Multiplier with op amp

    Your welcome
  16. Arouse1973

    Multiplier with op amp

    Its quite common to add logs to multiply two voltages using opamps. I would have to look into this further. I cant answer this right now. Adam
  17. Arouse1973

    Multiplier with op amp

    Yes but what output do you need? Adam
  18. Arouse1973

    Multiplier with op amp

    Hello what voltages are you trying to multiply, and why are you doing this? Just a basic amplifier can multiply voltages, why are you using a log amp. Explain more. Thanks Adam
  19. Arouse1973

    HUH?????

    Lol yeah same here. Adam
  20. Arouse1973

    HUH?????

    Nice to have a boss without a clue, think of all the goodies you could get for just saying it's to run an LED :) VNAs are a must when working on all circuits:) Adam
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