Question RE: NE555 pulse generator

[dwhitt]

hi,
Is this better.?

npn transistor and the push button.

Remember the SSR in my dwg is for simulation.

Connect the OUT to the 'real' SSR +in terminal and the SSR -in to the 0V line.

OK. I get it now! thanks for making it dummy proof for me . I will get the diodes and let you know how it works. Have a great weekend!

 

[ericgibbs]

OK. I get it now! thanks for making it dummy proof for me . I will get the diodes and let you know how it works. Have a great weekend! You too.!

This shows the SSR in better detail.

 

[dwhitt]

Thanks again. Sorry, one more question. What diode should D1 be? The 1N4006?

 

[ericgibbs]

Thanks again. Sorry, one more question. What diode should D1 be? The 1N4006?

Its not a diode its an LED, used for power indication, inplace of the lamp.!

 

[dwhitt]

Eric,
I appreciate all the time you have taken to help me with this project. If you don't mind, I have a couple of questions regarding your schematic.

The diode next to the counter - is that part of the counter model or does it need to be added seperately? If it needs to be added, do you know the difference between the 1N4006 and 1N4005? The 06 was not available at my local supplier.

It is working *mostly*. There is a feedback pulse meaning I get a count when I press the button and again a second later. Also, even though my input is 12V, the output pulse is measuring 30V. Right now I do not have the diode because I assumed they were part of the model but wanted clarification from you.

Thanks again.

 

[ericgibbs]

Eric,
I appreciate all the time you have taken to help me with this project. If you don't mind, I have a couple of questions regarding your schematic.

The diode next to the counter - is that part of the counter model or does it need to be added seperately? If it needs to be added, do you know the difference between the 1N4006 and 1N4005? The 06 was not available at my local supplier.

It is working *mostly*. There is a feedback pulse meaning I get a count when I press the button and again a second later. Also, even though my input is 12V, the output pulse is measuring 30V. Right now I do not have the diode because I assumed they were part of the model but wanted clarification from you.

Thanks again.

hi DW,
The diode has to be across the counter coil in order to suppress any back emf from the coil, it protects the transistor.
It can be a 1N4001... thru 1N4007 diode, all ok.

Your push switch is probably 'noisy' use a simple res/cap filter on the switch contacts.

The 30V problem sounds like a very poorly regulated power supply.
Try loading the output of the power supply, with say a low wattage 12V lamp, it should bring it down to around 12V.

Let me know how it goes.

EDIT:
I have added a simple switch filter. If your switch is very 'bouncy' [noisy] then you will require a better filter. Let me know.

 

[dwhitt]

I added the filter with the 100 Ohm Resistor and 100nF Capacitor. The button has stabalized a lot however, now the trig to the chip isn't getting any signal. It is measuring 12V in normal mode and when the button is pressed.

The most logical explanation would be a short to Vcc somewhere. I checked the wiring three times and everything seems to be correct so I am stumped again.

Just to be sure - the C5 capacitor (between the two 4kOhm Resistors) is 2nF right?

 

[sheldonstv]

heres a better switch debounce circuit using a 4093 .....this will clean up yr noisy trigger signal for correct 555 triggering pm me if u need any more help

 

[ericgibbs]

I added the filter with the 100 Ohm Resistor and 100nF Capacitor. The button has stabalized a lot however, now the trig to the chip isn't getting any signal. It is measuring 12V in normal mode and when the button is pressed.

The most logical explanation would be a short to Vcc somewhere. I checked the wiring three times and everything seems to be correct so I am stumped again.

Just to be sure - the C5 capacitor (between the two 4kOhm Resistors) is 2nF right?

hi DW,
The cap is 2.2nF, try increasing to 10nF.

 

[ericgibbs]

heres a better switch debounce circuit using a 4093 .....this will clean up yr noisy trigger signal for correct 555 triggering pm me if u need any more help

hi,
The draw back with your 4093 latch is that it requires a SPCO [two pole switch] for it to work correctly.

It would not work when using a n/o push switch.

 

[sheldonstv]

that is correct but the schematic can be altered to work with a normally open pushbutton...heres a schematici did a while back as part of a cctv controller,the circuit that provides the step signal would work...

 

[dwhitt]

that is correct but the schematic can be altered to work with a normally open pushbutton...heres a schematici did a while back as part of a cctv controller,the circuit that provides the step signal would work...

Hi Sheldonstv. Thanks for the schematic. Even though I am sure that is a perfectly good solution to my problem it would involve me starting completely over. Right now I would like to focus on altering what I have to try to get it to work. I will keep your solution in my files just in case I can't get this one to work. Thanks again.

hi DW,
The cap is 2.2nF, try increasing to 10nF.

Hi Eric. That seems backwards to me. I was actually thinking of lowering the capacitance. But you are the expert and I will trust your solution

 

[sheldonstv]

the circuit is just an add on for yr existing 555 schematic to cure any switchbounce that you may get with the schematic you have at present.........