555 astable

[colum]

I can not get this circuit to work I copied it from the internet and copied others from old magazines and they all overheated 555 and the power supply too. I show the physical layout in case that is the problem. All add ons are variable or replacable..Thanks for your help

 

[Nanren888]

Power supply faulty?
555 timer variant you are using ok with 9 volts?
Pots set to mid range to start? If 100k set to zero, in theory would short rail to discharge pin 7.
Shorts on board?
Chip the right way round?

 

[WHONOES]

I suggest that you have a good read of the datasheet, see link below, and then try some of the circuits contained in it.
I also urge you to dispense with all the pots and use fixed resistors until you are familiar with the device.

LM555 Timer datasheet (Rev. D)

 

[Audioguru]

If the 555 IC is not connected "the right way around" then it is a cheap, defective or fake one from "over there".
Buy genuine electronic parts from a real electronic parts distributor.

 

[colum]

Power supply faulty?
555 timer variant you are using ok with 9 volts?
Pots set to mid range to start? If 100k set to zero, in theory would short rail to discharge pin 7.
Shorts on board?
Chip the right way round?

GOOD point The chip has the round indentation next to the #1 - post I assumed
Yes I started the pots midrange
Thanks..colum

 

[Nanren888]

over there

Just to balance this last point from my own experience. This can be an issue, I know, but buying small quanties, 10, 50 at a time, I've used a lot of such chips including 555 timers purchased from China, personally and from Aliexpress, and not found any that misbehaved so far. Each of us has different experience.

 

[Nanren888]

Well, it's a bit of a mystery. Construction comes next. Did you make what you think you made?
The silly stuff: Battery the right way round? &c.

 

[colum]

If the 555 IC is not connected "the right way around" then it is a cheap, defective or fake one from "over there".
Buy genuine electronic parts from a real electronic parts distributor.

I will change my supplier for sure. Thanks..colum

 

[colum]

Well, it's a bit of a mystery. Construction comes next. Did you make what you think you made?
The silly stuff: Battery the right way round? &c.

I'm excellent at silly stuff but in this case its my 4th try and I never give up and I triple check. Thanks colum

 

[colum]

I suggest that you have a good read of the datasheet, see link below, and then try some of the circuits contained in it.
I also urge you to dispense with all the pots and use fixed resistors until you are familiar with the device.

LM555 Timer datasheet (Rev. D)

I made everything variable or replaceable because I'm not very good at math or schematics so after I determine settings
I redo the combinations. Thanks colum

 

[Bluejets]

Very seldom , if ever, do I have a problem with any of the "imported parts".

More likely the pots as mentioned earlier.

If you do not like/cannot do the maths, there are numerous online interactive calculators which will give you a variety of values, depending on which end you need to start from.

With just a square wave shown at the output, how will you know if it is indeed working..?
Do you have a cro.....?

No values on the caps either.

You say the power supply overheated and yet show a battery.

 

[Nanren888]

So, if all seems correct, you start trying to work out which part is not right, broken, not as expected.
.
Substitution. Swap each part for another similar.
Start with the ones that if this is not the broken part, that is, there is something else broken, you won't blow up your new substitute in the process.
.
Measured the power supply output? Actually 9 volts? DC?
So, changed the 555?

fixed resistors

Swap pots for fixed resistors, at least for now. Plenty of 555 astable calculators online to get values.
.
Something we should have asked earlier:
Er, what's the load on the 555 pin 3? A resistor and LED? scope?
Another: is it running & hot or just getting hot?
Able to measure the timing capacitor? Or swap it for another? Capacitor rated for at least 9 volts?
Guess you have checked for shorts in the construction.

 

[plutes]

is it because pin 7 goes straight to ground.

This website has a good 555 section, it may help
http://www.talkingelectronics.com/te_interactive_index.html

 

[colum]

Very seldom , if ever, do I have a problem with any of the "imported parts".

More likely the pots as mentioned earlier.

If you do not like/cannot do the maths, there are numerous online interactive calculators which will give you a variety of values, depending on which end you need to start from.

With just a square wave shown at the output, how will you know if it is indeed working..?
Do you have a cro.....?

No values on the caps either.

You say the power supply overheated and yet show a battery.

I know it is experimental and I have built complicated stepper motor drives by puitting in var pots and switchable caps and all hardwireing The power supply I was using overheated so it may be damaged thats why I used a battery but the 555 began to heat up Keep in mind this issue is new to this project only. I only buy 6 ics at a time so it may be vey cheaply made stuff

 

[plutes]

I know it is experimental and I have built complicated stepper motor drives by puitting in var pots and switchable caps and all hardwireing The power supply I was using overheated so it may be damaged thats why I used a battery but the 555 began to heat up Keep in mind this issue is new to this project only. I only buy 6 ics at a time so it may be vey cheaply made stuff

try it without attaching pin7, its internally grounded. Just going from what I read at talking electronics

 

[colum]

So, if all seems correct, you start trying to work out which part is not right, broken, not as expected.
.
Substitution. Swap each part for another similar.
Start with the ones that if this is not the broken part, that is, there is something else broken, you won't blow up your new substitute in the process.
.
Measured the power supply output? Actually 9 volts? DC?
So, changed the 555?

Swap pots for fixed resistors, at least for now. Plenty of 555 astable calculators online to get values.
.
Something we should have asked earlier:
Er, what's the load on the 555 pin 3? A resistor and LED? scope?
Another: is it running & hot or just getting hot?
Able to measure the timing capacitor? Or swap it for another? Capacitor rated for at least 9 volts?
Guess you have checked for shorts in the construction.

With out any load it heats up tp the touch and with a meter it heats up so I can not get a reading because this over heating is immediate. like a dead short all of the pots are tested the capacitors were tested in another circuit
It only leaves the 555 which I will get from another source. Assuming my schematic is good and all of the wiring is hardwired carefully

 

[Nanren888]

try it without attaching pin7

Sorry, don't understand. Pin 7 is usually the internal controlled discharge path, so the capacitor will not discharge if not connected to pin 7.

 

[Nanren888]

Coincidentally, I got handed the other day some old throw away boards labelled "RS 434-071" which are pre-printed (not populated) boards for 555 modules. These boards just allow you to build basically the same circuit on a PCB.
Not everyone's perfect option, but one way to have these useful little circuits always at hand.
.
Rather a slow option, but can send you a couple if you want.

 

[plutes]

Sorry, don't understand. Pin 7 is usually the internal controlled discharge path, so the capacitor will not discharge if not connected to pin 7.

I may be wrong but I think by his drawing he wants a square wave output, equal mark space you can ignore pin7 according to this book

 

[plutes]

I may be wrong but I think by his drawing he wants a square wave output, equal mark space you can ignore pin7 according to this bookView attachment 51307View attachment 51308

accidentally deleted this