What is the vertical scale, 2V/div?




Do you have a 0.1uF cap across the supply pins on the op-amp, 555, and switch (with a 1k pullup resistor on the non-grounded switch side). The switch cap will reduce bounce and possibly noise, while the others reduce noise on the power rails.

Microswitch has one common point , one Normally Open point & one Normally connected point.
I used first two points, so according to you I have to connect NC point to positive supply using resistor . And connect Capacitor across common point and NO point. OK?

 

Microswitch has one common point , one Normally Open point & one Normally connected point.
I used first two points, so according to you I have to connect NC point to positive supply using resistor . And connect Capacitor across common point and NO point. OK?

Just connect the 0.1uF cap across the switch in your schematic. Change the 10k pullup resistor (the one that connects to the switch) to 100k. The cap will discharge rapidly when you close the switch, but will recharge slowly, eliminating the results of bounce.

 

It looks like the tangle of wires on the breadboard are antennas and are picking up interference.

 

I am using non-electrolytic capacitor as timing capacitor connected to pin 7 of 555. Is it OK?

 

I am using non-electrolytic capacitor as timing capacitor connected to pin 7 of 555. Is it OK?

Sure. Why wouldn't it be OK?

 

Just connect the 0.1uF cap across the switch in your schematic. Change the 10k pullup resistor (the one that connects to the switch) to 100k. The cap will discharge rapidly when you close the switch, but will recharge slowly, eliminating the results of bounce.

Do you mean this type of arrangement with low values of Capacitor chosen...

 

Do you mean this type of arrangement with low values of Capacitor chosen...

Move the cap down to be across the switch contacts that close the circuit, rather than across the resistor.

It makes an RC circuit when switch is open, and only R circuit when circuit is closed, since switch is shorting capacitor.

 

Move the cap down to be across the switch contacts that close the circuit, rather than across the resistor.

It makes an RC circuit when switch is open, and only R circuit when circuit is closed, since switch is shorting capacitor.

Microswitch has one common point , one Normally Open point & one Normally connected point.
I used first two points, so What I will do with the unused third pin? Leave it opened...

 

Microswitch has one common point , one Normally Open point & one Normally connected point.
I used first two points, so What I will do with the unused third pin? Leave it opened...

Yes, leave the normally closed point unused, treat it as a SPST switch rather then the SPDT it is.

 

Move the cap down to be across the switch contacts that close the circuit, rather than across the resistor.

It makes an RC circuit when switch is open, and only R circuit when circuit is closed, since switch is shorting capacitor.

Actually I meant to design one RC differentiator as signal conditioner to trigger input to 555. For that input is given to one capacitor plate and output is taken across the resistor.

For your schematic it is not obeying. Is it a RC differentiator which producing spikes to Micro switch pulse input ?

 

Do you mean this type of arrangement with low values of Capacitor chosen...

No. See the attachment.

 

Thanks Ron, I will check the performance of debouncer circuit and report here.


We have disused about the slew rate and rail in/out capacity of the op-amp to sync with 1ms pulses ranging from 0-5V in 0.5V steps. Can 2N2222 power transistor sync with voltage levels and timings ? Is there any better options ?

 

Here is another one...

 

Thanks Ron, I will check the performance of debouncer circuit and report here.


We have disused about the slew rate and rail in/out capacity of the op-amp to sync with 1ms pulses ranging from 0-5V in 0.5V steps. Can 2N2222 power transistor sync with voltage levels and timings ? Is there any better options ?

If you keep the duty cycle low (1ms/625ms), 2N2222 is probably as good as any, and much better than some.

 

I dont want to connect a capacitor across a switch directly as the switch shorts out the cap when it is closed. That's not that good of an idea. However, with a small resistor like 100 ohms in series with the cap, all is well.

If I connect 100 Ohm in series with the capacitor across the switch, will it affect the Lower Threshold Point of Schmitt trigger inverter ?

 

I dont want to connect a capacitor across a switch directly as the switch shorts out the cap when it is closed. That's not that good of an idea. However, with a small resistor like 100 ohms in series with the cap, all is well.

If I connect 100 Ohm in series with the capacitor across the switch, will it affect the Lower Threshold Point of Schmitt trigger inverter ?

I could have sworn I replied to this, either here or on ETO.
100 ohms will work well.

 

It gets very confusing when this guy posts the same questions on multiple websites.

 

It gets very confusing when this guy posts the same questions on multiple websites.

If others were participating, it would be understandable, but you and I are the only ones responding. I think I will stop responding to the thread on ETO.

 

Actually my 555 output at 10 V is greater than 5V and I used 50K POT to adjust it to the required level at load. For example take output from 4.5V leg of ladder and adjust the 50K POT to get 4.5V across the load. Without disturbing the set value of POT take output at all other voltage positions. One time adjustment is applicable for all voltage levels.

If I have exact 5V at top of ladder then this one time 50K adjustment is not required. For that I can use the cases you said, or 74121 / 74123 ICs as they can output exact 5V.

If I have exact 5V at top of ladder(by using 74121 instead of 555) then resistors of the ladder should be have 0.01% tolerance levels for equal divisions of this 5V.
My doubt is then the 50K in parallel with them could change the balanced condition of the ladder. Thus no equal voltage divisions takes place. Can I avoid this by placing 100K or 1M ohms (>> 1K ladder) in place of 50K without disturbing both ladder and the op-amp.

If I avoid POT and connect op-amp directly to ladder , then floating condition would be resulted between switching intervals of ladder outs.

 

Can I use any resistor network ICs to simulate the role of good tolerance resistance ladder ?

Can I use any analog MUXs to switch voltage levels from 0 to 5V in 0.5V steps between ladder and output driver transistor ?

Can I use Make-Before-Break contact having NOT latch instead of debouncer using capacitor across the switch as shown below?