555 Toggle On / OFF Switch

[N.G.]

I got a question about the Toggle ON / OFF Switch author: Michail Papadimitriou

The ne555 can operat from 3-18V, can i use a 12V relay and power all with 12V, do i need to change some of the resistor values ?
Sorry for a my noob question but i dont have mutch experience with the 555 ICs.

http://www.electronics-lab.com/projects/misc/012/index.html

 

[Hero999]

No, just  connect it up and it will work.

T1 isn't needed though, the relay can be connected directly between pin 3 and 0V but you still need D1 to protect the 555 from back-EMF.

By the way, you do realise there are lots of better ways to make this circuit?

Are you planning to leave it connected to a battery for long periods of time so it can be used as a power switch?

If you use the CMOS 7555 and higher value resistors, you can save a lot of power. Another option is to dump the 555 altogether and use logic gates e.g. CD4001, CD4011, 74C14, 74C04 or better still, a flip-flop IC such as the CD4013 or a CD4028, all of which are cheaper than the 7555, it depends on what parts are available to you.

By the way, the standard 555 has a maximum voltage rating of only 4.5V to 16V, the CMOS ICM7555 has a voltage range of 3V to 18V.

 

[N.G.]

I got a bag full of ne555 and the cmos version too (is not the texas instruments version but some cheap china stuff) and i want to use a it with a infrared led and a "infrared sensor" (it got 2 pins, i guess is a fototransistor that operates in ir domain) and i will make a reflective sensor, when you move the hand abou it the ir light will reflect back to the sensor and it will trigger the toggle. Fore better range i pulse the led at around 38khz with a 555 (lucky i found a nice application that makes all the math for me and gives me directly the resistor and capacitor values i need for the timing the i asked). The CD4013 is ideeal for this but it got a major drawback, if i pover him at 12v it will need a trigger voltage of 12v too. There i will need to use a transistor or a op-amp. The transistor whud be easy, but i need 1 that whud accept a lower voltage at base and is capable of conducting 12v from C to E, any ideea on a common transistor that can do this ?

PS

The project is intended to run from a 12 power supply and act as a switch for 220v application.
Thanks for your help.

 

[Hero999]

I don't know what you're talking about as far as the transistor is concerned or why you still can't use the CD4013 or omit the transistor and connect the relay between pin 3 and 0V.

All silicon transistors have a base voltage of between 0.6V and 1V depending on the base current.

If anything, the 555 circuit is more of a pain to trigger than a flip-flop, a push button switch, analogue switch or solid state relay are your only options because the switch needs to be able to conduct in both directions, you do realise that you can't just rip out the switch and replace it with a phototransistor?

 

[N.G.]

Can you please give me a reference schematic for CD4013 that operates a 12v relay with a trigger voltage  between 0.6V and 1V ? And what can i do if my IR motion detector made from IR led and the IR sensor (it looks like a black led, even the pin length difference is same) gives under 0.6V ? shod a put 1 more transistor before the trigger transistor or shod i build a 1 transistor audio amp and use it ?