This is a stroboscopic light that uses LEDs and has the advantage of being battery powered. You can regulate the pulse from 0.1 seconds up to 1 second.
Components list:
B1-4 - 1.2V (Ni-CD or Ni-MH) or 1.5V (carbon-zinc or alkaline) battery;
C1 - 1.0uF tantalum capacitor;
C2 - 10nF ceramic capacitor;
D1 - 1N4001 rectifier diode;
D2-13 - Nichia NSPW510CS LED;
IC - 555 timer (LM555, NE555 or equiv.);
R1 - 120K carbon resistor (5% tol., 1/8W);
R2 - 1M variable resistor (10% tol., 1/8W);
R3 - 12K carbon resistor (5% tol., 1/8W);
R4 - 82Ohm carbon resistor (5% tol., 1W);
R5 - 1Ohm wirewound resistor (5% tol., 3W);
T - TIP32 PNP bipolar transistor.
Notes:
- The rectifier diode D1 and the switch S2 seem to have no pursose, but they have (yesterday I thought it too, but then I remembered their purposes). D1 serves here as a zener diode, causing a voltage drop when S2 is switched off. I did this because rechargeable batteries (Ni-CD or Ni-MH) have lower voltages than the non rechargeable ones. Since we are talking about white LEDs that have a relatively high voltage drop, and thus their brightness can vary greatly with respect to changes of the supply voltage, then this solution is more adequate. I just calculated R5 considering the use of rechargeable batteries, and D1 serves when normal batteries are used (actually I used that kind of arrangment in another project and I will post it in another post, just for reference).
- R2 is used to regulate the pulse. For R2 you could use a potentiometer instead. In some places potenciometers are easier to find than variable resistors. When using a potentiometer tie one of the end legs to the cursor leg (just for reliability), and you will have a variable resistor).
Components list:
B1-4 - 1.2V (Ni-CD or Ni-MH) or 1.5V (carbon-zinc or alkaline) battery;
C1 - 1.0uF tantalum capacitor;
C2 - 10nF ceramic capacitor;
D1 - 1N4001 rectifier diode;
D2-13 - Nichia NSPW510CS LED;
IC - 555 timer (LM555, NE555 or equiv.);
R1 - 120K carbon resistor (5% tol., 1/8W);
R2 - 1M variable resistor (10% tol., 1/8W);
R3 - 12K carbon resistor (5% tol., 1/8W);
R4 - 82Ohm carbon resistor (5% tol., 1W);
R5 - 1Ohm wirewound resistor (5% tol., 3W);
T - TIP32 PNP bipolar transistor.
Notes:
- The rectifier diode D1 and the switch S2 seem to have no pursose, but they have (yesterday I thought it too, but then I remembered their purposes). D1 serves here as a zener diode, causing a voltage drop when S2 is switched off. I did this because rechargeable batteries (Ni-CD or Ni-MH) have lower voltages than the non rechargeable ones. Since we are talking about white LEDs that have a relatively high voltage drop, and thus their brightness can vary greatly with respect to changes of the supply voltage, then this solution is more adequate. I just calculated R5 considering the use of rechargeable batteries, and D1 serves when normal batteries are used (actually I used that kind of arrangment in another project and I will post it in another post, just for reference).
- R2 is used to regulate the pulse. For R2 you could use a potentiometer instead. In some places potenciometers are easier to find than variable resistors. When using a potentiometer tie one of the end legs to the cursor leg (just for reliability), and you will have a variable resistor).
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