pushbutton switches/555 timer

If I understand correctly, pin 3 of the 555 turns on an NPN xistor and the xistor collector is connected to the toy? if this is the cas,e you can wire up individual xisitrs for each toy, these are called open collector outputs and the voltage form each toy will stay with each xistor.

Overall it sounds to me like you want a simpler overall solution, maybe a selecor switch to select the toy.... or just 4 individual switches for each toy...... keep it simple for these kind of things is usually better...

Mark

You might want to use relays. A relay is a device that is basically an electronic switch. If you put some voltage across two of the connectors, it'll close a switch connecting the other two connectors. The nice thing is that the switch side doesn't care what the voltage is, so this solves your multiple voltage problem.

So, for each toy you want to provide, you need

1) a small, 5V coil relay 2) a diode (like a 1N4001) 3) two small NPN transistors (2N2222A seem to be available at Radio Shack) 4) a 100k resistor 5) a 220uF capacitor 6) a 1Meg Ohm resistor 7) a pushbutton that is normally open, and closes when you push it.

What will happen is that the pushbutton will turn on the circuit, and once you let go of the button, the capacitor will discharge through the 100k resistor at a given rate. After between 10 and 20 seconds, the transistors will turn off the relay, and the toy will turn off.

button | RELAY ---

5VDC------ ---o----o---. 5VDC--o--. | | | | |.--+ TOY SUPPLY -. | | \\1MEG - )| 3, 6, 9... | | | / ^ )| .-------. | 1\\ 2 | \\ | |'---|-TOY + | | 0/ 2--- / c--o---o--' | | | 0\\ 0--- '-b | .---| TOY - | | k/ u | e | | '-------' | \\ F | | c '----------------' | | '-b | | e GND-----------o----o---------'

No 555 is needed. If you can get a 'darlington' NPN transistor, you can use that instead of the two NPN transistors. The package will show the pin connections; they are 'collector', 'base', and 'emitter', corresponding to the 'c', b', and 'e' on the diagram above.

Also, the 220uF cap will be an electrolytic cap. They have a + and - side. Make sure the - side is on the ground.

Finally, if you get a 220k ohm pot instead of the 100k resistor, and hook it up so that the 'trimmer' is attached to one of the other legs, so it has 2 pins, you can adjust the timeout by changing the resistance. Did that make sense?

Answered elsewhere and via E-mail; did you receive it?

Ed