This is of course the simplest electronic code lock circuit one can make. The circuit uses one transistor, a relay and few passive components. The simplicity does not have any influence on the performance and this circuit works really fine.
The circuit is nothing but a simple transistor switch with a relay at its collector as load. Five switches (S0 to S4) arranged in series with the current limiting resistor R2 is connected across the base of the transistor and positive supply rail. Another five switches (S5 to S9) arranged in parallel is connected across the base of the transistor and ground. The transistor Q1 will be ON and relay will be activated only if all the switches S0 to S4 are ON and S5 to S9 are OFF. Arrange these switches in a shuffled manner on the panel and that it. The relay will be ON only if the switches S0 to S9 are either OFF or ON in the correct combination. The device to be controlled using the lock circuit can be connected through the relay terminals. Transformer T1, bridge D1, capacitor C1 forms the power supply section of the circuit. Diode D2 is a freewheeling diode. Resistor R1 ensures that the transistor Q1 is OFF when there is no connection between its base and positive supply rail.Circuit diagram.
Notes.
This circuit can be assembled on a Vero board.
Switch S1 is the lock’s power switch.
The no of switches can be increased to make it hard to guess the combination.
Transistor 2N2222 is not very critical here. Any low or medium power NPN transistor will do the job.
Read more: http://www.circuitstoday.com/one-transistor-code-lock#ixzz1PA2yxZbN
Tv Remote Jammer
Here is the circuit diagram of simple but highly effective TV remote jammer circuit.
Most of the TV remotes have 38KHz operating frequency. A flood of IR beams in the same
frequency can easily confuse the TV receiver and this is the operating principle of our
jammer. The circuit is nothing but an astable multivibrator based on NE555 IC. The
output of NE555 is amplified using a PNP transistor SK100 to drive the IR LEDs. Not only
TV remotes, but any IR remotes operating in the 38KHz frequency region can be also
jammed by using this circuit.Circuit diagram.
Notes.
The circuit can be assembled on a Vero board.
Use a 9V PP3 battery for powering the circuit.
Mount the IC on a holder.
POT R4 can be adjusted to exactly match the jammer’s frequency to the remotes frequency.
This adjustment is very essential for effective jamming.
Read more: http://www.circuitstoday.com/tv-remote-jammer#ixzz1PB4sofv5
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