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Momentary Switch Teamed With Latching Relay

This circuit allows an SPST momentary pushbutton to act as a push-on push-off switch, using a DPDT latching (bi-stable) relay. It was originally intended to allow a single pushbutton switch on the dash of a vintage car to provide a latched function. The relay only draws current when it is being switched. At other times, the only current drain on the 12V supply is the leakage current of one 22µF capacitor, which is very low. It works as follows.

Assume that initially the latching relay is in the reset state, with pins 4 and 6 connected together. In this state, C2 charges up to +12V via 2.2kO resistor R2 while capacitor C1 remains discharged as it is not connected to the 12V supply. If S1 is pressed, C2 discharges via the relay’s “set” coil, diode D2 and S1. This switches the relay into its set position, connecting pins 4 and 8. C1 then begins to charge via R1. While S1 is being held down, the relay does not return to the reset position because the current supplied via R1 is insufficient for the coil to latch the armature. As soon as S1 is released, current no longer flows though the coil so C1 can finish charging, ready for the next button press.

Link:http://www.extremecircuits.net/2010/06/momentary-switch-teamed-with-latching_03.html

Be the first to comment - What do you think? Posted by admin - January 1, 2011 at 7:38 pm

Categories: Electronic Control Tags: circuit switches, latching relay, relay-switch

Touch Switch low cost by Timer IC 555

This Touch Switch circuit use a part compares with voltage 2 group , within the integrated circuit timer LM555 or NE555. For perform wait for catch the change of voltage , which be born from way leakage touches by change a finger. When the value is Resistance at drop the pate which build with pin 2 of the integrated circuit is valuable are down the level is Voltage output (pin 3). Will have the condition voltage high for apply the work and other circuit next. The detail is other , a friend sees in the circuit yes.

Be the first to comment - What do you think? Posted by admin - October 15, 2008 at 7:35 am

Categories: Electronic Control Tags: circuit switches, LM555, touch-relay-switch

CMOS 4013 Switch

The voltage generated by a piezo transducer can activate a digital circuit. One may build a simple demonstration switch from a piezo transducer and a 4013 D type flip flop (see Figure 12). Each time the piezo film is hit, it triggers the 4013 turning the LED on and off on alternate triggers. While this circuit works , it is unreliable, due to the waveform of the generated piezo pulse signal. To a digital circuit, a piezo-electric pulse will resemble a switch bounce with decay (see Figure 2).