richard.c

Hi,

Have at look at the following link, it gives a very detailed account of the 555.

It also gives some simple diy circuits including a 10 min timer - just what you want.

http://www.uoguelph.ca/~antoon/gadgets/555/555.html

hth

Hero999

I do agree it isn't the best place to buy stuff from but it can be handy, especially for beginners.

Unlike shopping on the Internet, you can actually see and handle the parts before you buy them.

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Krumlink

You can still make a working timer though using radiosharks parts.

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MechTronics

World of Warcraft is a disease

audioguru

RadioShack ripped off too many people in Canada. They are gone.
The Source by Circuit City are now running some of the RadioShack stores.

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Uncle $crooge

Krumlink

I agree with ripping off people that dont know better. They need to:
1. Leave the electronics sales
2. Leave the home entertainment sales
3. Leave the Crappy christmas toy sales
4. Give all their junk back to china
5. Fire all their staff and re hire them as pig farmers

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MechTronics

World of Warcraft is a disease

Hero999

They need to:

1. Stop selling Crappy products.
2. Start selling hight quality products.
3. Stop selling things at rip-off prices.
4. Start selling thigs at reasonable prices.
5. Sack all their brain dead staff.
6. Employ decient staf who actually know something about electronics.

Well I don't know about Radio$h@g as they left the Uk a few years back but Craplin's need to do all of the above.

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busines5

Yes, I found that page a little after posting on this board. It says all that's needed to make the simplest timer is a 555 timer, a resistor and a capacitor. And I believe I can change how much time it will countdown or up by using resistors and capacitors with different values. That's good.. I'll play around with different resistors and capacitors once I figure out how to hook it up. BUT, I need some help there. I can't seem to figure out those diagrams, like this one that belongs to that simple timer I just mentioned.

Here's what I think I figured out so far from that diagram..

I take the red wire from a 9V battery clip and connect it to pin 8 of the 555 timer. I take the black wire of the battery clip and connect it to pin 1. I connect a wire from pin 3 to one of the legs of my electric match and connect a wire from the other leg of the match to the black wire of the battery clip. Now the rest I just don't get. It looks like there's a wire connected to the red wire(from the battery clip to pin 8) that connects to a leg of the resistor. (Does it matter which leg?) Then from the other leg of the resistor it goes all the way to the positive leg of the capacitor(I assume capacitors are to be hooked up the right way) and it looks like wires from pins 6 and 7 are hooked up to it along the way. Then we connect a wire to the negative leg of the capacitor and connect it to the black wire of the battery clip(or 'ground' if you will).

So how's my aim?
Go easy on me, ok

audioguru

You are almost correct.
1) The max allowed output current from a 555 is 200mA. Your "electric match" might draw more which needs a power transistor to handle the high current.
2) You must trigger the timer by causing its trigger input pin 2 to go low for a moment. You also must make pin 2 high when it is not being triggered.

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Uncle $crooge

richard.c

Please see you PM box.

ramoni

hey pals, show me adiagram for a timer without using 555, could you?

audioguru

Timers:
10 Charge a capacitor from a resistor and use a FET-input opamp to measure the voltage rising.

2) Charge a capacitor from a resistor and use a Scmitt-trigger Cmos gate or inverter to switch when the threshold voltage is reached.

There are probably many other ways to make a short timer.

A long timer is made with an oscillator/counter IC like a CD4060 or a CD4541.

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Uncle $crooge

RetiredHAL

Hi, I stumbled across this thread "googling" Kitchen timers ccts.
I don't want to appear paranoid, but what is "busines5" trying to do here ? Make a simple 10 minute delay to fire a rocket or set off a bomb. He is obviously completely ignorant of any electrical or electronic knowledge and is asking to be spoon fed how to start from scratch. His opening post wants a simple circuit to fire a rocket after 10 minutes. ??????? How far away does he want to be before firing the rocket?

Cheers RetiredHAL
PS Nice Site

audioguru

A single 555 doesn't make a delay for him to run far away before his diy rocket explodes. Its output goes high immediately when the button is pushed.
The timing of a single 555 is how long its output stays high after being triggered.

He needs a second 555 to be triggered when the first 555 times out. Then the second 555 drives a power transistor that lights the electric match.

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Uncle $crooge

RetiredHAL

Hi, audioguru, you are right, about needing more parts than one 555 ic.

My point is, that to ignite a rocket (and I presume this to mean fireworks) you light the 10 sec fuse which is luckily attached to the rocket when you buy it and move away 15 metres and watch it go up in the air. I have problems imagining where one would want to set up a rocket, press the button and wait 10 minutes to see it ignite!!!

Cheers
RH

EvilGenius

Hi boys and girls.

Not to make things more complicated but I saw a simple and cool timer circuit for rockets using 555 timer and 4017 and a few more parts. You can adjust the time with a variable resistor and connect the outputs of 4017 via resistors to drive 9 LEDS (7 green, 1 yellow, 1 red, and last bit for boom. That way you can actually see the timer in action and prepare for it (day or night). There was also a safety switch used in series to the main positive feed to shut down the whole thing just in case.

By the way they sell all sorts of kits similar to this idea cheap online if you search for it.

Cheers