power toggle using tact switch

[ultra242]

hello all.

i'm new to the community and i hope to become a contributing member as i learn more about electronics. i'm currently in my first year of EE and also am a hobbyist.

i have been looking for a certain schematic and i'm hoping to find it here. i'd like to use a tactile switch as a power toggle. the tact switch should held for 1/2 to 1 second before toggling the power. the power supply is 9v (needs to output 9v) and i'm drawing about 1A in the circuit.

does anybody have a ready made schematic for this by chance? i'm new enough that i can't make a schematic based on part recommendations, so i'm looking for something specific. thanks!

drew

 

[k7elp60]

hello all.
i have been looking for a certain schematic and i'm hoping to find it here. i'd like to use a tactile switch as a power toggle. the tact switch should held for 1/2 to 1 second before toggling the power. the power supply is 9v (needs to output 9v) and i'm drawing about 1A in the circuit.
drew

So you want a 1/2 to 1 second delay to energize power after depressing the switch. Then you want the power to stay on.
Do you want depress the switch again to turn the power off?

 

[ultra242]

exactly! something reliable as this is for my sequencer.

 

[ljcox]

There have been several posts on this subject.

Have you searched this forum using key words such as :- "momentary switch", "flip flop", "toggle", etc.?

For example, see https://www.electro-tech-online.com/threads/t-flip-flop-to-turn-on-off-led-w-tact-switch.32798/

 

[ultra242]

in fact i read that exact post. i didn't see anything with a delay on it.

 

[k7elp60]

The attached schematic should do the job. With the 10M resistor and the 3.3uF capacitor on pins 67 of the timer the time is about 40 seconds. I suggest a cmos version of the 555 so you can use a larger value of capacitor and hence a lower value of capacitor. I have found with the 555 too large of timing capacitor has excess leakage current and the timing could be off.
The IRF9530 is a pchannel MOSFET.
The 100k and 0.1uf capacitor connected to pin 2 of the 555 prevents the delay starting with applying power. The 0.1uf capacitor and the 100k resistor connected to pin 8 of the F/F prevents the load from being connected also when the power is connected.
The 2N3904 inverts the 555 timer output to drive the F/F

 

[ultra242]

thanks a lot! i now have a couple suggestions that i'm going to try. we'll see where this goes.

ultra

 

[ljcox]

in fact i read that exact post. i didn't see anything with a delay on it.

The post by Krumlink has a delay. It would have to be altered to give a one second delay.