Intro: Ghost Busted
“Eanny beany chilly beany the sprits are about to speak.” Ok so my wife didn’t fall for it, she knew I did something to make the LED turn on and off and no matter how hard I tried I couldn’t convince her I was communicating with Bob the radio operator of the RMS Carpathia a ship torpedoed in WW1 and famous for rescuing the survivors of RMS Titanic. However it did give me the chance to practice Morse code.
I got the idea from damianzuch; he wanted a remote system for playing practical jokes. I thought of IR remotes over radio remotes for size and security reasons, IR remotes have a less chance of being accidently triggered in public.
The first circuits I came up with worked but the receiver miss fired a lot so I tinkered with it and came up with 5 IR receiver circuits that did different things and 3 small IR transmitters you can hide in your hand. And the reason for 5 different circuits is size the first circuit if powered by button batteries can be hidden in a match box the last circuit might need a tool box with batteries.
Step 1: IR Transmitters
These are small and simple, with small button batteries they can be hidden in a large gaudy ring or in the palm of your hand like I did here.
There is a little variation in IR LEDs some run on 3 volts some run on 6 volts with a resistor so you may need to tinker to get the transmitter just right.
Step 2: Transmitter & Receiver Parts & Tools
1. IR LED.
1. Small push button switch.
2. 3 volt button batteries.
1. Battery 9 or 12 volts.
1. 1N4001 diode.
1. LM78L05 voltage regulator.
1. IR sensor.
1. DM74LS14N Schmitt trigger hex inverter.
1. SN74LS73A JK flip flop.
1. 2N3904 NPN transistor.
1. BT137 Triac.
1. PC817 Optocoupler.
1. Colored LED.
2. 220 uF 16 volt electrolytic capacitor.
1. 100 uF 10 volt electrolytic capacitor.
1. 1 uF 10 volt electrolytic capacitor.
1. 0.1uF ceramic capacitor.
2. 330Ω ¼ watt resistor
1. 1kΩ ¼ watt resistor
1. Bread board or proto board
Step 3: The First IR Receiver Circuit
When you depress the button on the remote this circuit turns on the led and remains on for 0.5 seconds after you release the button, perfect for doing Morse codes dots and dashes. The circuit can be broken down into 4 parts, power supply, IR sensor, one shot, and load.
In the power supply the 78L05 IC regulates the voltage to 5 volts for the IR sensor and ICs.
The IR sensor picks up the signal from the transmitter and sends it to the one shot.
The one shot receives an irregular signal and converts it to a clean square wave output, this one shot is a favorite of mine, it is very simple the larger the capacitor the longer the output signal, this one is 0.5 seconds.
The load on the output of the ICs is low only 5 to 15 ma.
Step 4: The Second Circuit
The second circuits work like the first circuit only the addition of the transistor allows you to drive a light, small motor, or solenoid up to 200 ma for a half second or more as long as the button on the remote is depressed.
Step 5: The Third Circuit
The Third circuit, works like the first circuit, however the third circuit with the addition of the optocoupler and Triac will drive a light, motor, or a solenoid that runs on 8 amps for a half second or more as long as the button on the remote is depressed.
Step 6: The Fourth & Fifth Circuits
The fourth and fifth circuits are not made to work with solenoids; however the transistor and the Triac will drive loads the same as the second and third circuit will. However with the addition of the JK flip flop when you press and release the button on the remote once the circuit turns the light or motor on and they will stay on. It is only when you press the button on the remote a second time the light or motor turns off.
And now you are ready to make your friends and family into believers.