key chain laser power supply

[steven2]

in these pictures  are a simple modified power supply to power a keychain laser with.    now  the keychain laser takes about  3x button cell batteries and , if i was to power it from just a plain battery the laser will have a short life span so the idea was to measure the 3 buttoin cells battery voltage and try get as close to as i can with the same  voltage so to start with i used a simple 5 volts output regulator circuit and with a bit of exsperimenting i  was able to get 4.66 volts output of which seemed to work ok at powering the laser with .    at the positive output i solderd a 1n4148 diode and after that a ten ohms resister so thats how i got the 4.66 volts output so the diode and resister helped to reduce the voltage and or current  output from the regulator circuit  now the keychain laser i dident have to dismantle like ive done before as the tiny board at the front  has a small flatt peace on it and it has a tiny wire from it thats solderd to the main board so if that tiny wire burns off, if i power it with the wrong voltage , and then that tiny board will fall off.  the laser is so tiny you cant see it it must be sandwhiched into the board so you think its not there , now by removeing the battery cap end by screwing it off, inside is a thin circular plastic insulator and the spring which the bottom of the batteries sit on  now with a insulated crockadile clip  with a wire solder to it i sqeeze it open and insert it into the opened battery end where the batteries normally go in , and i clip it onto the spring so thats one terminal supply and for the other well you cant use the keychain laser body so  you strip a wire and wind it around the removable head that has a lense in it  that goes into the front of the keychain laser and tape it to it or wind the wire around the inner section where the  lense cap is pushed onto so thats the second  terminal now the keychain laser has a great long range and i can  piont the laser light all the way down the road  and through the windows of a block of units and onto the wall and further if i dident have any biuldings in the way, now thats just the laser powerd by the simple modified 5 volts output circuit, from a 9 volts battery and the receaver for the laser is  a light activated or vise versa circuit which is in another topic in the forums  somewhere called fairchild photo transistor data, which has the circuit to use as a receaver, now this receaver as ill call it responds to laser  light more better than sunlight and infrared so i can trigger the light activated relay from a long distance away  useing the keychain laser, now the idea of these 2 circuits is to make a long range laser break beam detection circuit that can be triggerd if something or someone walks through the laser and the relay in the light activated relay circuit will be triggerd thus switching on a long range fm transmitter or alarm  so this i plan to improve it and would come in handy  for detecting the american bigfoot or the australian version, the yowie , ,is why ive been working on this and to compensate for false triggering by smaller animals a second laser is spaced from the first and at a distance a second light activated relay circuit , now to do some long range laser to reaceaver alignment  can be done with a peace of white cardboard

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[steven2]

with the on button on the keychain laser taped down the on switch is left on and i used a small on off slide switch  at the battery clip to switch it on with

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[steven2]

hers some more better pictures, in these pictures ive retaped the wireing to the keychain laser and allso ive included the light deactivated relay circuit  so when the laser beam to the light deactivated relay is broken the relay switches on and turns on whatever is wired to the relay

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[steven2]

heres another view and this time the switch hasent fallen down on its side as i had it held in place with blue tac

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[steven2]

the last 2 pictures aint comeing up so click on the download link at the bottoms to download them to view them and send them to your documents and open them there if you cannot open them

 

[ante1]

Hi Steven,

There are no problems viewing your pictures. Nice project, how far can this beam reach? Doesn’t it need any shielding, some kind of tube or alike to protect against other light sources?

 

[steven2]

ante the dark activated circuit s relay is kept open by the laser shining into the fairchild photo transister and the transister can be housed in a peace of black tube so no other light can set it off unless it shines into the tube but ive got it set so the laser triggers it only  but ill find out for sure next time i do some more testing, the laser keychain shines that red laser spot a really long distance  so i just need s ome long distance space to find the maximiun distance the laser can trigger the sensitive realy circuit from and ill add it to this topic  first ill need to get a nice size houseing for it  all and one long dark street as this one we live in is around 100 meters geussing, long and the laser i can shine down the end and through the windows of a block of flatts so ill keep doing some more testing

 

[ante1]

Ok Steven, Ill await the test results then. ;D

 

[steven2]

ok ante hey  you can light up the rear reflector  of a car from a long distance way to

 

[steven2]

here are some more pictures in this one is a redraw of the siutable  circuit with the adition of the relay which is different  the relay here is wired up with a separate 9 volts dc input , so when the keychain laser is aligned with the photo transiter, the led turns off.  and ive yet to make some more modification so as to include other circuit aditions so that the circuit can transmitt warnings or alerts ,when the laser is broken

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[steven2]

here is a closup of the circuit and allso the  whole setup of the prototype

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[steven2]

View attachment 37320

 

[audioguru2]

Hi Steven,
How far is its range? I got a laser pointer in a pen and it can light-up a car's reflective licence plate at night very far away. The reflection is nearly blinding.

If your 9V batteries are new, and the forward voltage drop of your red LED is 1.8V, then you are feeding 41.5mA through it and it might melt with such a high current. Most red LEDs are recommended to use only 20mA.
Your 390 ohm resistor is dissipating 673mW, but looks like its max rating is only 1/2W. Isn't it smoking? I dare you to touch it. ;D

Why use 18V to light a 1.8V LED? You are throwing away 16.2V to heat the resistor with your expensive batteries.

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[audioguru2]

Hi again,
I use http://maps.google.com to measure the range of my stuff. It's too bad it its fine detail is only for North and South America and England right now. I can see the map or switch it to a satellite picture. I was excited to spot my house with my car in the driveway and my son spotted a jetliner flying over a neighbourhood.
Most of the rest of the world is shown including Australia, but the detail isn't fine yet. ;D

 

[steven2]

audio guru the circuit that drivers the keychain laser is a regulater with its output reduced to afe level enougth to power the laser, froma 9 volts battery which isent at full 9 volts and the regulater wont allow any more than 5 volts if i had more than 9 volts input, and even if it was fed 12 volts from my lead acid cell batteries it puts out exactly 5 volts and with just the 9 volts battery with under 9 volts left in it i get just the power i need to power the keychain laser without burning it out. as for the receaver circuit or light deactivated realy it tuns off a 9 volts battery to that has less than 9 volts left in it and as for the led thats not runing off the circuit as its only run through the relay contacts from a sepparate  9 volts battery that hasent the full charge and is under it  and for the led 390 oms at 1/2 watts is sufficient to power led from a 9 volts battery that hasent got 9 volts in it and theres no heat generated whats so ever , even if the battery had the full nine volts theres no heat  i did try another circuit before to get 4.35 volts for the laser but dispte what the circuit said, when i biult it it did not put out what the circuit said it would  so i ended up modfying a simple regulater to do it right  and it worked from biulding it not from theory or circuit that was probabaly drawn but not tested, as for the 21 volts i think you mentioned  where did you get that from  im useing 9 volts battery with well under there rateings and the light deactivated relay circuit uses 2 x9 volts batteries and the yellow coloured relay voltage rateing is  much higher than what the 9 volts batteries have in them  and even the current rateing to  and ac rateing to  and dispite useing such low voltage the relay is working ok so ill asume the voltage rateings are minimim  to operate the relay  with the low voltage  of well under its stated voltage rateing

 

[steven2]

corection you say 18 volts not 21 well the 2 batteries aint runing in parralell or sieries and dont have full charge in them ive got them sitting in parralell or sieries but they aint wired the same remember one battery powers the laser in the laser circuit and one powers the relay circuit and the last battery is just wired in through the relay contacts in such a way that when the laser shines into senser the light goes out so that is my indication of perfect laser alignment into senser  and when the beam is broken the relay turns on and the led comes on and whatever other circuit i add to it latter

 

[steven2]

i forgot to mention the keychain laser dose shine a very long distant in the dark and untill i can find a street long enougth  in the dark without any inturuptions i can get a better idea but ive had a keychain laser years ago and the best i can geuss from shineing it down a long road was a quarter of a kilometer or over , no tape measure long enougth to measure that and i think  with the keychain laser i have the voltage of the 3 button cell batteries is closer to what ive managed to get with the output from the circuit to power it and somehow i think if there is a max voltage input before the laser burns out then i must be under it and the laser is brighter to 

 

[audioguru2]

Hi Steven,
Your schematic shows four 9V batteries. 2 in series for 18V for the photodtector/transistor, and 2 more in series for the 390 0hm resistor in series with the LED.
It is very confusing when it shows "-9V" instead of ground. ;D

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[steven2]

and yet it all works perfect with no over heating, my friend.