Instructables
Picture of Delay timer
P4060337.JPG
This is a delay timer using a simple 555 timer. that will keep a eg. fan, light, motor running for a preset period after a designated trigger is activated. (e.g keeps your computer CPU fan running for another 5 minutes to cool after pc is off)

Go easy on me this is my first tute:P

Disclaimer: i take no responsibility for any issues you may encounter using this product.

there prob wont be any but just covering my ass:P
 
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Step 1: Components and pcb

2 pin terminal block *3
Capacitor (ceramic preferable) = 10nf
Electrolytic capacitor 220uf = 16v
1N4001 diode
555 Timer
IC socket (8pin)
DPDT relay (MUST BE DECENT QUALITY)=12V
N-channel MOSFET(varies according to job)
Resistor = 33k
Resistor = 10k
Resistor = 100k
Resistor = 1k
Resistor = 51R
Potentiometer (PCB mount) = 1M

PCB of course or breadboard if you wish to test first
be aware if you wish to have the output hooked up to a motor you may need different fets to the one listed and also may need another diode to protect it, DC computer fans dont have current spike problems. feel free to ask me any questions and ill do my best to answer them for you.

Its up to you of which method you pick to get your circuit, i have used a photoexposure process and a veroboard, both work ok, the veroboard was more compact but it was messy and dirty.
zarmons6 months ago

hi you there, what is the value of the transistor? you did not mentoin it.

thank

jhager42 years ago
ohhhhh and I need it to be ran from a motion sensor cant figure out how to change this from AC to DC (from basic 110 V motion sensor)
jhager42 years ago
ok I'm not to wise when it comes to this ,,but ,, I need to make a 555 timer with a delay and a reverse to change polarity , I am making a prop i used a drill and have it rewired to go to my 12 V batt. i have the start , stop covered I think , I just need to know what resistor (s) I need and what (relay(s) to do this.
so over all I need this to run a cycle of about 1 to 2 sec. then pause for about 10 sec then reverse ,and reset. so start ,stop, delay ,reverse ,reset is wut i need it to do can anyone help with this??
gunspyop22 years ago
cool do you have any other detinater timers that use risitors
dash244 years ago
what was the numbr of dat resistor 51R..  wats dat??an ohms??rply plz.
pero27 dash244 years ago
51R means 51 ohm, yes; this is the standard in electronics; M-mega (10^6), k-kilo (10^3), R-just ohms (multiplied by 10^0 = 1)
dash244 years ago
 dude,, is this timer must be use in any appliances?? for example the television is on then the brown out came,. if I put that delay timer on t.v, is it possible?? reply asap..plz.. 
dellconn4 years ago
Hi thanks, but how if i just need for 5-10 seconds delay for led project? any suggestion?
Arooj4 years ago
itx nice..!

can yew tell meh the formation of pulsating dc using 555 timer ic?
TOMMY8934 years ago
Hi, I'm an old guy and I used to make up circuits and such, I've not done this for many years but I suddenly decided to do it again as a hobby, I used to make a 555 dummy alarm, they run on a 1,5 V nicad which lasted for many months, I can't remember the components other than:- 555, CAP,LED and I don't remember. PLEASE CAN ANYONE HELP ME WITH THE CIRCUIT. THANK YOU
aakiem5 years ago
thank you, i am try another aplication
galkaen5 years ago
Nice project! I will like to make a timer for a hydroponic system that switches on for one minute, and four minute off. Is it possible to run 120V ac with this?
Argon275 years ago
Neat I've been looking for instructions on how to do this for a while. Just an idea but couldn't you take a kitchen timer and just solder the speaker leads to the object to use it as a timed switch?
chainsawz5 years ago
can you change the time limit and can you use it for other things like leaving a room and making the light turn off 3 minutes after you leave?