need help: 0V triggered circuit to generate 5V

harryperales · Feb 20, 2009

need help: negative going pulse triggered circuit to generate 5V

hi guys,
im very new to electronic stuff. i just would like to know if is it possible to generate a 5V voltage from a single short pulse signal of 12V (50ns duration).

i need help for some sort of circuit to receive the 12V short pulse and have the circuit generate a steady 5V which i will use to power another TTL circuit.

regards,

harry

blueroomelectronics · Feb 20, 2009

You can't have a 0V pulse. It has no potential.

harryperales · Feb 20, 2009

ooopsss, sorry my bad.

i mean a 12V short pulse signal from an electronic coinslot that i have. i need to be able to generate a 5V from this to power another TTL based logic circuit which would in turn communicate with my PC via parallel port

blueroomelectronics · Feb 20, 2009

Just clamp it with a 22K resistor & 5.1V Zener.

crutschow · Feb 20, 2009

harryperales said:
i just would like to know if is it possible to generate a 5V voltage from a single short pulse signal of 12V (50ns duration).

Unless the 12V is from a very low impedance source you won't be able to generate much 5V power from a single 50ns pulse.

blueroomelectronics · Feb 20, 2009

Agh I missed that part. How often does the 50ns pulse repeat?

KMoffett · Feb 20, 2009

harryperales said:
generate a 5V from this to power another TTL based logic circuit which would in turn communicate with my PC via parallel port

Do you actually mean that the 12V/50nS pulse needs to power the Vcc of the circuit, or just trigger the 5V input in a circuit that is already powered by a 5V power supply?

Ken

duffy · Feb 20, 2009

50ns from an electronic coin slot??? I've used coin mechs (standard and electronic) and even built optical coin detectors - none of them had that brief of a pulse.

harryperales · Feb 21, 2009

KMoffett said:
Do you actually mean that the 12V/50nS pulse needs to power the Vcc of the circuit, or just trigger the 5V input in a circuit that is already powered by a 5V power supply?

Ken

i just need to use the single pulse generated by the coin slot to trigger the power on another circuit, because it already has it's own supply

harryperales · Feb 21, 2009

blueroomelectronics said:
Agh I missed that part. How often does the 50ns pulse repeat?

there is only a single pulse from the electronic coinslot... variable from 20ns, 45ns and 60ns

blueroomelectronics · Feb 21, 2009

Then use the resistor diode clamp as described in my first post.

ericgibbs · Feb 21, 2009

harryperales said:
there is only a single pulse from the electronic coinslot... variable from 20ns, 45ns and 60ns

hi,
Use a HEF4528 dual monostable, powered from +12V, set the period of the mono to suit 'expanded time period' required.

Say extended output period of 500mSec, which could control a 5V system via suitable transistor.

Is this what you are asking.?

duffy · Feb 21, 2009

What type of coinslot is this that generates a 20-60nS pulse? Are you sure you're reading that spec sheet right? This is a whopping five orders of magnitude faster than any unit I'm familiar with.

harryperales · Feb 22, 2009

the brand is SR. it's written on the box of the coinslot so im sure that it's 20-60ns

ericgibbs · Feb 22, 2009

harryperales said:
the brand is SR, i think it's made in china. it's written on the box of the coinslot so im sure that it's 20-60ns

hi,
With respect to the Chinese note regarding the 20-60nS I would suggest using a scope to check the pulse,, I would.

Details can get confused in translation.

harryperales · Feb 22, 2009

ericgibbs said:
hi,
With respect to the Chinese note regarding the 20-60nS I would suggest using a scope to check the pulse,, I would.

Details can get confused in translation.

i already did that and got the same result, i had a friend of mine bring it to school just to make sure of the pulse.

also, im not pointing out china in a bad way since im using mostly items from china. It's only there in the event that there maybe someone who also brought similar item's who could help me out. i have great respect to chinese because my boss is a chinese...

ericgibbs · Feb 22, 2009

harryperales said:
i already did that and got the same result, i had a friend of mine bring it to school just to make sure of the pulse.

also, im not pointing out china in a bad way since im using mostly items from china. It's only there in the event that there maybe someone who also brought similar item's who could help me out. i have great respect to chinese because my boss is a chinese...

Why dont you post a simple circuit showing ideally what you want this pulse to do.

harryperales · Feb 22, 2009

i am currently in an internet cafe now so it would be difficult for me to make a simple circcuit and then attach a picture here.

basically what i wanna do is to generate an output that is suitable for the parallel port lets say for about 1 sec so that my software will be able to detect the generated signal from the coin mech

i have an idea but i don't know if it's possible so i'll just ask for your ideas

1)directly send the negative going output pulse to LM555 (configured as a monostable) trigger and then feed the output of the monostable to the parallel port

ericgibbs · Feb 22, 2009

harryperales said:
i am currently in an internet cafe now so it would be difficult for me to make a simple circcuit and then attach a picture here.

basically what i wanna do is to generate an output that is suitable for the parallel port lets say for about 1 sec so that my software will be able to detect the generated signal from the coin mech

i have an idea but i don't know if it's possible so i'll just ask for your ideas

1)directly send the negative going output pulse to LM555 (configured as a monostable) trigger and then feed the output of the monostable to the parallel port

I did suggest a HEF4528 dual monostable in a previous post.

Im not sure if a 555 is fast enough to respond to 20nSec trigger pulses.???

duffy · Feb 22, 2009

ericgibbs said:
Im not sure if a 555 is fast enough to respond to 20nSec trigger pulses.???

I'm not even sure the cable is fast enough to respond to a 20nS signal.

I've also never heard of "SR" as a coin mech manufacturer, and I notice you didn't post a model number or anything.

need help: 0V triggered circuit to generate 5V

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