need circuit schematic

Anyone have the circuit schematic for this kit? (or anything like it)

**broken link removed**


I basically need a timer circuit that turns something on after X amount of time, and when you turn it on its default needs to be off. Also, it needs to stay on once the time has elapsed.

If anyone has a schematic that is the same as the one above but also uses a 7-segment display please give me the link/picture. thanks

timer

hi,

what you need is a timer operated in a monostable mode. as to timer formulas check out my post dated Jan.14, 2004. it would be very useful to you.

try http://www.discovercircuits.com

bd13 said:

Anyone have the circuit schematic for this kit? (or anything like it)

**broken link removed**


I basically need a timer circuit that turns something on after X amount of time, and when you turn it on its default needs to be off. Also, it needs to stay on once the time has elapsed.

If anyone has a schematic that is the same as the one above but also uses a 7-segment display please give me the link/picture. thanks

Click to expand...

that's an astable 555 timer circuit. the formulas for it are given in the description, it simply uses a resistor, a pot, a capacitor, and a 555 timer (which is an 8 pin IC that is used in many many many many things...)

google "astable 555 timer" (without the qoutes), and many schematics will come up for it, the pin layout and scematics will be the same, the formula is given in the description of that circuit to figure out the time (if you want to use a resistor instead of the pot to create a fixed time)

adding an 7 segment display to that... um... i don't see that happening... would have to change the 555 timer to trigger every second, put it through a counter, which would control the 7 segment display somehow, and once the counter reached a certain preset number, it'd trigger your device... or something along the lines of that.

it's late, and i gotta get going, but if you are interested in a simple schematic for a astable 555 timer circuit, and can't find one with google... i can pull one up for you. along with the needed resistor and cap values.

plot said:

bd13 said:

Anyone have the circuit schematic for this kit? (or anything like it)

**broken link removed**


I basically need a timer circuit that turns something on after X amount of time, and when you turn it on its default needs to be off. Also, it needs to stay on once the time has elapsed.

If anyone has a schematic that is the same as the one above but also uses a 7-segment display please give me the link/picture. thanks

Click to expand...

that's an astable 555 timer circuit. <snip>

Click to expand...

Plot, that looks like a monostable to me, as Mozikluv said. They call it a countdown timer, but I don't think it actually counts. The equation tells the story, as well as the picture. Looks like a 555 to me.

Check www.ozitronics.com and look under timers. You should find something that meets your needs exactly, except it only has a 4 digit read out. However, it the timer 4 digit timer does cycle between minutes and hours so you can see hh:mm:ss:TH on the display.

Ron H said:

plot said:

bd13 said:

Anyone have the circuit schematic for this kit? (or anything like it)

**broken link removed**


I basically need a timer circuit that turns something on after X amount of time, and when you turn it on its default needs to be off. Also, it needs to stay on once the time has elapsed.

If anyone has a schematic that is the same as the one above but also uses a 7-segment display please give me the link/picture. thanks

Click to expand...

that's an astable 555 timer circuit. <snip>

Click to expand...

Plot, that looks like a monostable to me, as Mozikluv said. They call it a countdown timer, but I don't think it actually counts. The equation tells the story, as well as the picture. Looks like a 555 to me.

Click to expand...

at first i thought it was a monostable too, but looking at the equation... i thought for a monostable it would be 1.1RaC, and for an astable it would be .7(Ra+Rb)C which is what's given on that website for the calculations. maybe i have monostable and astable mixed up?