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Posts posted by Um...Me123

  1. I want to make a sensor that is wires to the sheet metal of a car body that when touched can activate something such as a 555 or a piezo (to be determined later).

    How do touch lamps work?
    Can I apply this to a car body somehow?
    Any ideas?

    I don't want an alarm system to go off or anything but just a little beep or something to warn people my car is "smart" and not to be messed with.

  2. I have heard (and seen in a movie) about devices that pick up a sound, invert it, and play it back out to create destructive interference resulting in silence.  Apparently this is how noise canceling headphone that Bose makes work.  I just want to try to make a small device that you can point at something (has to be close by to keep in sync) and make it silent.  Nothing complicated.
    How do I use a transistor to invert the signal then how do I use a small 8ohm  .5w speaker to cancel it.
    With a small speaker that has next to 0 watts I should be able to make fairly quiet noises become silent (like whispering).....right?
    It's just an idea out there...

  3. Ok....Installing an amp and sub for my friend in his little beater  :P  Anyway he kept telling me about he heard something about drilling through his firewall.  I kept saying naw and you just run it off a 12V feed like a cig. lighter.  (My previous research was in the thought of putting speakers in my boat where this wasn't an issue.)  How many amps does an amp draw?  The wire kits I saw were 10awg wire that goes to the batt. for a 200w amp.  Is this fully necesairy (probably) or can I power it with the cig lighter wires?  I think his amp is putting out 150w continous (RMS) bridged for 1 sub.
    The kit is needed then?

    P.S. Anyone happen to know what the remote turn on wire (from deck to amp) runs through it?  If the kit doesn't come with it, what size of wire would work there?

  4. Is there an esy way to build a tiny remote that will turn on/off almost anything via infrared (capable) such as TVs, projectors, sterios, etc.?
    Is there a simple 555 driven frequency for an infrared LED?  I know different brands have different codes but I saw this little keychain remote that said it would do on/off, volume, and channel for any TV.  I want to attempt to build it but due to my not so good knowledge of electronics I just want to tackle the on/off if possible.

  5. I have a "What hapened?" question:
    I was powering my inverter with my PSU (you know what I'm talking about audioguru) and as I turned the knob up i started to hear the buz of the inverter then the wire came on dimely with a loud buz then a little higher voltage and the wire came to full brightness and quieter.  I heard a pop and thought i felt the inverter make a little jolt (of viberation) and I unpluged it quickly. A bad smell and a little smoke came out of the holes where the wires are,  I thought I saw the wire stay illuminated after the pop.  I opened up the little box and the only noticable thing on either side of the board is a small cap that seemeed like the little rubber/plastic coating around it had squished down to the bottom and the top half was just silver then.
    Anyone know what appened?
    The PSu when hooked up to the DMM make spikes to a hgh voltage then down to where it should be when raising the level.  I thought it was just the meter.  Maybe I surged it?
    O well...someday...ka-boom!

    Question:  Why is there a  :-* icon??  Ha HA  An electronics forum?!

  6. I guess you misunderstood me.  The supl yto the fan and meter do not go through the LM317.  I know 38 is way to high thats why I was asking about the resistors.  I thought the 38 might drop down when a load was put on the regulated portion.  Anyway...I think I figure it out myself.
    Thanks anaways

  7. Wow everything you said there was very confusing.  I need 5V @ 110mA for the fan and 9V (8-12) at 1mA for the meter (but it's not working (see other topic))  The fan is a 40mm and fits nicely on top of the heatsink (to give you an idea of heatsink size) So I don't believe heat is a problem.  I just need to know if I should base the calculations for the fan on 38.5V.  Meaning I would need 300 ohm at 3.7 watts for the fan.  As for the meter, if it decides to work,  I would need 30,000 ohms at some very small wattage.  Would this be correct?

  8. Hi all.  I was the one who put the LM317 in backwards and blew it and the pot up  ;D ::). 
    Anyway I got new parts and finally put it together and got it working.  I want to power a fan and a voltimeter in the unit but I don't know what to base my resistors on.  I have a pre-regulated wire that come ut of tthe circuit after the bridge and smothing cap.  I believe my trnsformer is 24V @ 2A but I can't remember cause it's been a while since I worked on this.  Thing is-I get a reading of 38.6VDC off that wire?!  I'm not swimming in parts like alot of you so I picked up any old handy resistor that happen to be a 220 1/2w and it made no difference in the reading at all?  ??? What's going on and how do I figure out what voltage to use to figure out what resistors to use for my fan and meter.

    This was with no load on the regulated output wires (its a shared neg.).  I guess I never checked to see if changing the pot would do anything?

  9. I hooked up a brand new inverter and the same wire didn't work.  I used the wire to line the edges of the panel of buttons for a project of mine.  It gets used in the dark and this is an impressive way to light it.  The wire is bent about the corners fairly sharply.  How does the wrap wire short if the core wire is coated and (I think) has a small layer of insulation?  It can't short itself out can it?  The didi work for a while and now its totally unresponsive (no flickers - nothing).  I'll go test the origional inverter more but I'm pretty sure it still works.  I have a very messy work area and a bad memory but I mealieve it was the rest of the wire (not on the panel) that I lit with the origional inverter.

  10. Quick question:  I ran 1.5V more than recomended (at 1A besides ::)) into an inverter driving EL wire.  It was also only about 1/4 of the length of wire that came with the inverter.  It caused the TV in the room to go all fuzzy (didn't happen with a smaller power supply or the full length) and the wire flickered then quit.  I finally figured out the inverter is just fine so I figure I did something to the wire.  Could I maybe have just fried part of the smaller wrap wire or did I burn al the phosphor coating on the copper wire?  Mainly I want to know if there is anything I can do ir the wire toast?

  11. I have some extra speaker wire from a long time ago and I don't know the AWG.  I need to extend two 70W 4ohm speakers about 16ft. and 10ft.  One is about twice the size of the other but same wattage.  The provided speaker wire is a larger AWG than the extra I have but I also don't know it's AWG.  Is there a way to know if the wire is ok or not?  What happens if the wire I add is too small?  Can I do a resistance test throughout the wire and somehow tell if it's ok?

    P.S. The longer extension is for the smaller speaker if that helps.

  12. I need to make a driveway monitor that blasts a piezo indoors when someone comes in the driveway.  (I am making this for someone) their driveway is maybe 1000ft. long  or so.  I figure I could have a IR led powered with a 555 and bateries on side and the other side could have the IR photo diode.  Since I want to use just one 24 awg wire to run to the house (a radio signal strong enough sould be to hard od a project for me and probably use to much battery power) I may need a transistor with another battery(ies)? to transmit though all that small wire?  Inside I want to use maybe another transistor with activate a 555 monostable to set off a 2 tone piezo.
    I need help on the schematic because I don't have experience with transistors.  NPN PNP ?? ahhh!!!!!

  13. They way the system is there are several positives to multiple nichromes and one negative and the LED and push button is on the negatove side.  Therefore, pushing the buttons (the multiple ones) does a continuity test but if you hold down the one button and press one of the others causes a fire (then its safer that way also).
    Thanks for your help.  Im not giving a full descripton at this point of the project because I am working on posibly marketing this.  It's not to hard to figure out but my design is much easier to use then home-made ones and safer because of the good parts (not just a touch and fire)

    I am using RF-45 cables because I can get them very cheap in the 100' length.  Otherwise the cables can be very expensive.  I have another question:  I want to make another box with a much simpler design for fireworks that can be launched at a closer range.  I want to use parallel cable because of the 25 wires and the wide (or once was) use then can be cheap.  I have a hard time finding a 25' or so parallel cable on ebay (the cheapest by far).  Al the cable are parallel to printer.  The parallel side is 25 female and the printer side is 36 (i think) male.  How does that work???  If I cut off the printer connection will there be 25 or 36 wires in there?

  14. Sorry I should have wordered the questions differently.  I was meaning when 13.5V @ 1A with the right resistor is applied to a LED what is the resulting mA comming out of the - lead?

    About the pushbutton:  What I meant was a SPST NO pushbutton wired in parallel with the LED and resistor.  Would this waste? The reason for the bypass is because I need the max power for my ni-chrome but also want to be able to test the connections without lighting the ni-chrome.  The ni-chrome only needs to be red hot for about 1 second so will the waste use enough to cause a no light?

  15. I have a quick question and Ill delete this topic after I get an answer.  How many mA do I get out of a LED?  The same ammount as it draws?  Less than that?  Or supply minus the draw? 
    The max supply I may have is 13.5V @ 1A.  I am using a LED as an indicator(with a proper resistor) of a complete circuit but will have a pushbutton to bypass the LED.  I want as little of mA as possible to result (when not bypassed).  (I am powering ni-chrome so if I get to much...BOOM if it's hooked up ;D)

  16. I'm sorry I have to ask such a dumb question but every othere resourse is eplaining how to uses caps and resistors in AC and can't (to a full extent) answer my question.
    I can't figure out what AC is.  I know what it stands for and that it goes at 60Hz.  I used to think there was a positive and a negative and the positive turned on and off at 60Hz but after learning about bridge rectifiers and seeing many otherr things I pretty sure its the polarity reversing itself at 60Hz.  (AS in lead 1 is + and lead 2 is - then lead 1 is - and lead 2 is + and so on)  Is this right?  I almost always am working with DC circuits but I stumbledd along a problem while wiring some outlets in a PSU.  I have 2 (light) switches and 2 outlets and I want to control the oulets with the the switches.  What I've done so far is wire the 2 black wire screws (on the 2 outlets) together (which is my mistake i think) and wired the white wires through the switches.  Then the mains that comes from the wall goes to the 2 outlets black wire and to the 2 switches.  In a DC circuit this would be fine but i think  I have it wrong...Maybe...if the power is being supplied to both black wires half the time but it has nowhere to ground because the white wire switch is off then I'd be ok for eing able to switch it right?
    Thanks guys--if this is too confusing due to my wording I could make up a quick schematic for you if you like.

  17. Couple questions:
    If I want to make infrared filters (blocking visible light) I need to get unexposed but developed film? right?  And you use 2 layers?

    Is the voltage going to the LEDs (the red and the IR) affected by the opamp (I dont really know anything about them)?  So if i want to use more than one IR LED in parallel (for example) can i mess with the resistor values figuring for 12V in?

    If i want more than one recieving diode can i just out more in parallel or do i need to change something?

    Where do i find a opamp?  I live in the US and want to get my parts from www.allelectronics.com and if somethings not availiable there, from the local radioshack.  Can someone find an opamp on all electronics for me cause i couldnt and i guess i dont know wha im looking for.

    I got to go and i think i have more questions. thanks

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