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

 

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?

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The great thing about electronics is unlimited ways to do the job. The only limit is one\'s imagination. I generally think my way is best.
Show me a different way. I have an open mind.

 

exactly! something reliable as this is for my sequencer.

 

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 http://www.electro-tech-online.com/g...ct-switch.html

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Len

 

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

 

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

Attached Images

PWR on delay.GIF (17.2 KB, 21 views)

__________________
The great thing about electronics is unlimited ways to do the job. The only limit is one\'s imagination. I generally think my way is best.
Show me a different way. I have an open mind.

 

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

ultra

 

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

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Len