Two buttons provide safe start


Posted on Feb 25, 2013

The circuit in Figure 1 provides a safety interlock that checks the actuation of two pushbuttons before enabling a relay. When you push both buttons, the circuit actuates the relay. At that point, you can release one of the switches without the relay`s switching off. The circuit was intended to lock out the engine of an underwater propulsion unit. When handling such units on the surface, a person might accidentally press the actuator switch, which is mounted inside the handles of the propulsion unit. ANDing two switches makes the unit safer but requires two hands, a situation that is sometimes unsuitable.



Using the circuit in Figure 1, you need two hands to start the engine; once the engine is running, one hand is sufficient to keep it running. When you press no switch, the engine shuts off. The circuit uses a simple 555 timer, IC1 in a unique way. In thi




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Broken Charger-connection Alert
PIC16F628 as digital Tachometer
10 Watt TDA2002 Amplifier Circuit
5800 Xpressmusic LCD Screen Display Problem Repair Procedure
Regulated Dual Power Supply Circuit Using Regulator IC
simple automatic street light system
irf44 mosfet based on 100 watt
UltraSonic Radars
90S2313 AVR Robot Board
ISL8107 Single-Phase Pulse-Width Modulation (PWM) Controller with Wide (9V-75V) V
20w rangkaian audio amplifier tda7240
2 transistor buffer
FIRE SIREN USES FLASHER



Top