What can you do with a timer 555 ?

[ElectroNewby]

I don't know what to do with them.

What's the best way to get familiar with them and find useful things to do with em ?

 

[Reloadron]

A Google of "555 Timer Projects" will bring up literally hundreds of circuits and designs with a focus on the 555 in all of its variations. Additionally a Google of "555 Timer Books" will bring up a few hundred books on that single chip. Considering the hundreds of applications for the 555 and its variations your question is a little hard to answer. Get creative.

Ron

 

[alec_t]

Think of any situation where you may want to time something, or set a delay. Providing the time period is minutes or less a 555 on its own will be a good candidate for the timing IC. For longer periods a 555 IC plus a counter IC may be used.

 

[Blueteeth]

Ehhh, 'applications of the venerable 555'. The internet is full of pages, some completely dedicated to this little chip - and rightly so!

Aside from the usual time delay monostable, or square wave astable, and PWM, I've used these little bad boys for a number of things. They're cheap, readily available (literally everywhere) and have some basic building blocks that can either be used on their own, or together. For example, the output stage can drive a nice ammount of current, I've used it for MOSFET driving, not external components, really just a high current buffer. The two opamps inside form a convenient window comparator. It can be used as an RS latch, and can be the basis for very cheap (and not always efficient) switch mode power supplies. step down, step up, even sepic tologies can be done with a stock 555, albeit with frequency limits.

.... low battery circuits, power supply sequencing, charge pump converters, panel indicators, adjustable clocks for low-speed logic.. the list really does go on.

There are often much better ways o doing things, but for cheap and simple 'sub circuits' where there are few limitations it has myvote.

 

[alec_t]

even sepic tologies can be done with a stock 555

I've not come across those. Please explain.

 

[Blueteeth]

I've used the 555 for a boost converter, and with a coupled inductor (one of those coiltronics, dual winding jobs), converted that to a sepic converter. Its obviously not going to compete with chips specifically deisgned for the topology, but the use of crude current sensing with a transistor, the 555 is used as an oscillator, N-channel mosfet driver, and the 'reset' (inverted by an NPN) for feedback loop. So ultimately with the addition of passives, and a few transistors, forms the basis of a rather nice converter.

Buck works on the same principle, but with a high-side current limit.

The main limit is frequency, as the stock NE555 gets funny when it gets to around 200kHz. The CMOS versions work at higher frequnecies, but their output stage isn't up to the job of driving mosfets.

I only really started to look at these for switching power supplies as a way of becoming familiar with LTspice, was impressed by the results (read: wanted to confirm) so I knocked up some test circuits on stripboard. I'll dig out some LTspice circuits from my other computer if you like, nothing special, and not my idea ('flybacks for dummies' webpage sparked the idea, I just added current limiting so I didn't fry anything).