Panel switch wiring

The schema above above makes use of the CMOS 4017 decade counter IC. Each depression of a switch steps the output through 0– 9. By coupling the output via an AND gate to the next IC, a predefined code has to be input to create the output. Each PBS switch is de bounced by tw1o gates of a CMOS4001 quad 2-input NOR gate. This ensures a clean pulse to the input of each CMOS4017 counter. Only when the correct number of presses at PBS Awill allow PBS B to become active. This is similar for PBS C and PBS D. At IC4, PBS D must be pressed 7 times. Then PBS C is again pressed 7 times, stepping from output 1 to output 8. The AND gate formed around CMOS4081 then goes high, lighting the LED. The Reset switch can be pressed at any time. Power on resetis provided by the 100n capacitor near the reset switch. Below is a picture of one that I made about 15 years ago:  

Unfortunately, this board was part of a much larger project containing multiple power supplies. One day whilst working on another schema , I slipped with a wire and splashed 24volts DConto this board. There was a small spark, and puff of smoke before all this chips were cooked! If anyone does consider building such a schema, then my advice would be to stop and lookin your local electronic parts catalogue. There are now dedicated combination lock IC`s with combinations many time sgreater than this schema. Incidentally the number of combinations offered here is 10 x 10 x 10 x 10 x 9 = 90,000.Check out Dean White`s Electronic Gadgets, on the Electronic Sites Alliance web ring, he also has a combination lock schema.

Electronic Schmitt Trigger with Programmable Hysteresis Circuit Diagram. In electronics world, a Schmitt trigger is a comparator schema with hysteresis, implemented by applying positive feedback to the non inverting input of a comparator.

Electronic Schmitt Trigger with Programmable Hysteresis Circuit Diagram CA 3088 is used as a versatile Schmitt trigger. The size of the hysteresis levels is determined by Ia that flows out of the amplifier`s output and through R2. Increasing Ia increases hysteresis and vice versa. The positive and negative hysteresis levels are symmetrical about 0 V.

This is the electronic siren schematic diagram which used 2 transistor BC547 and BC557. The siren is powered by 9V battery or power supply adapter and use 8 ohm speaker to produce the sound. The siren is controlled by the touch plate switch. If you touch the plate, then this electronic siren will be activated. 

This is a given electronic schema with LEDs, to roll the dice just push the button. The electronics also ensures that no one can try to improve their lot by messing with the data. The key component of the data is a digital counter, an IC 4060 (IC1). This IC has a phase oscillator integrated so that only two resistors (R7, R8) and one capacitor (C7) is required to generate a clock. 

The clock signal is divided, and the division is called CT in the design of IC symbol. For example, the output signal CT3 (pin 7) is a square wave with a frequency equal to the clock frequency divided by 23 (8). The clock signal is divided by 24 (16) in the outlet CT4 for 25 (32) CT5 output, and so on. This means that the output signals form a binary number.