Motorbike Safeguard using Combination on Turn Signal Switch

After a couple of times making burglar motorcycles safeguard that use only transistor as active component, now is the time we make a slightly more sophisticated 😀 We will use digital CMOS components namely, 4017 decade counter, 4081 quad AND, and 4069 hex Inverter. These Components are widely available in electronic stores and the price is very cheap.

The workings of this circuit is very simple. The Q9 output of the 4017 is used to activate the relay. Reset of the 4017 is linked with an inverter U2:F which is used as a Power On Reset. Thus, when first turned on, the active Q of the 4017 is Q0.

To be able to reach the Q9, it takes 9 x clock pulses. This pulse can be obtained from the button A or button B. From the button A and button B, the first circuit is a 100K resistor and 10uf capacitor. This circuit is used to get a clean pulses. From the circuit of capacitors and resistors from the button A and B then are combined into one through the diodes 1N4148 towards a circuit of schmit trigger formed using two inverter U2:A and U2:B, two resistors R9 and R10, and a capacitor C7 and resistor R3 to ensure input from this schmit trigger gets low input when no buttons are pressed. This circuit will adds the stability of the pulse. From this schmit trigger, output was given to a circuit of one shoot which was formed using a AND gate U3:D, capacitor C4 and resistor R4, where its output was feeding back to the input of the schmit trigger using a diode D18. This one shot circuit is used to get a narrow pulse from the button A or B presses which is almost certainly the presses will be long enough (in milli seconds). The output of one shot is then used as the input pulses for the 4017. Thus, in order to make the active Q is Q9, it takes up to 9 x keystrokes of button A or B.

But remember, besides it is connected to the Clock input, this pulse is also connected to the Reset input of the 4017 through a gate AND U3:C where one of the input AND gate is connected to two gates AND U3:A and U3:B. One input from U3:A is connected to button A, and an input of U3:B is connected to button B. Now note that input of U3:A and U3:B has the the opposite condition of each other. This input is connected to the output of the dip switches to set the pattern of button presses. Note that if the active output from the 4017 is connected to the inputs of U2:C, then an input of U3:B will be low, while an input of U3:A will be high. And conversely, if the active output of 4017 disconnected from U2:C, then one input of U3:B will be high and one input of U3:A will be low. These design will determine how we should choose whether button A or B should be pressed so that the counting of 4017 can go up.

If the active output of 4017 disconnected from U2:C, then the button that must be pressed in order to make the counting go up is button A. Keep in mind that because one of the input of U3:B is high, so if the pressed button is button B, then the second input of U3:B will be high. Thus the output of U3:B will also be high. And note that the output of U3:B is connected to the input of U3:C where the other input is connected to the output of one shoot. If the inputs of U3:C are both high, then the outputs which is connected to the Reset of the 4017 will also be high. And this will cause the counting to be returned to Q0.

If the sequence of the dip switches which is connected to U2:C from Q0 through Q9 is set to ON, ON, ON, OFF, ON, ON, OFF, OFF, OFF, then the sequence of keystrokes is B, B, B, A, B, B, A, A, A. Only by this order so the Q9 can be active. This is equivalent to a variation of as much as 2 power 9 or 512 variations. A sufficient amount of variations to be solved in a short time. And as in the circuit of Motorbike Safeguard that uses Touch Sensors, you can also add a circuit of alarms on this circuit.

After the Q9 active, then one the input of U3:D that is used as one shoot will be low. Thus, keystrokes, either A or B, will have no effect anymore.

The use as a circuit of a motorcycle safeguard

You can just make a panel to put the buttons A and B at an easily accessible location on your motorcycle. But in my opinion it would be more interesting if we use the switch of turn signal as replacement of button A and button B. So, your motorcycle need not change the appearance.

The connection of switch of turn signal lamp is as shown below:

Note that this connection is similar to the connection of button A and button B, except that from the switch to the positive source is through flasher first. Therefore, we need to equate it by dispose the flasher circuit for a while using a relay.

Because we need a relay to make this switch to be in accordance with the order of the buttons A and B, then we replace relay RL1 with a double switch relay. During the relay that is not yet ON, the motorcycle can not be switched on, so the motorcycle will not require any turn sign lamps. So we can make it not functioning for a while. After the relay ON, then the turn sign lamp will return to work normally.

An addendum which may need to be aware of is that because button A and button B now have loads of sign lamp, then the value of the capacitor 10 uF for C1 and C2 may be too small. So maybe you need to replace it with a larger value, such as 100 uF. Try it with this value, whether a clean pulse or a spate of pulses is generated when we turn on the right or left lights. If the resulting pulse is a clean pulse, then the value is sufficient. But if the resulting is a spate of pulses, then try to replace it with a larger value.