i need help to make a simple timer

hello guys:)
i need to build a timer with multiple outlets which i can start from my computer. this sounds very simple to do for may of you robot builders but to me it is impossible to build one without help. i need to know what to buy for the board so i can make it start power outlets. i would surely need a relay and clock on the board but i really know nothing about this. i can weld electronics basic backup batteries or so i can learn i know wat a multimeter is and all i need to know how to do is a multiple outlet timer:) thanx in advance for any help

If i understand this righgt, you want to send messages to Arduino from he PC, and based on the messages turn some relays on or of ?

If you have as little experince as your post suggest, i would start out with a simpler project. First try to send messages to Arduino to turn LED’s on and of, this is quite easy, and not as dangerous as starting with relays.

To do this all you need is the Arduino board, some LED’s and some 470 ohm current limiting resistors. And of course some software on the PC to send the messages.

When you can control the LEd’s, thes you can step up to controlling relays. Arduino can not directly control relays, they draw too much current, so you need to control the relay via a transistor. There are many many examples online on how to do that.

well i have very little experience in electronic boards but i’ve worked with relays a lot and i work the relays on timers i buy. but what i need to do now is my own timer because timers are expensive and have limited number of outlets. it will be no problem in terms of danger i will be able to do that. if you have a link for a faq or a tutorial on how to do it it would be of great benefit to me:) thank you for your help

should the timer run on the PC or on Arduino ?

What is the “resolution” of the timer. Seconds ? minutes ? hours ? days ?

How many realys are you going to control ?

Two good places to check out :

the timer would better be on my PC like a software to control the signals on my arduino board which i send to the relay. i want to be able to control 30 power outlets or so and the resolution i need to be able to control it in seconds. i will check the links:)

:slight_smile: MikMo thx my friend this is a very useful diagram i got there. i can understand some things on it but still have to figure it out. i understand that i need to get an arduino digital out and a resistor1k or 2.2k then the circuit goes into the “base” i dunno wat this consists of. then the “emitter” also i dont know what exactly it is. they didnt specify a certain type of base or emitter so i guess theyr uniform below emitter is the ground connection and theres also the arduino ground linked to it. above i see the “collector” dunno wat it is from there up to the relay i don’t know what the letters stand for nor the numers 16 and 1 written on the circuit. i know one of the letters is for the transistor and for my purpose i need to get the TIP102 transistor since i have to power 220v electric currents. of course i will need the right software to control all this too. thanks again for the held :slight_smile:

The base, emmitter and collector are the 3 pins on a transistor.

You need a transistor to drive the relay, because Arduino’s digital pins can only source 40mA, which is too little to drive the relay.

Most relays could be driven by a TIP120 transistor.

This pdf explains the TIP120 very well, they use it to control a motor, but the principle is the same as for a relay.