Question about wiring a 555 chip

[tallan]

Hello Everyone,

Well I have a circuit on the breadboard that I saw in the projects forum here. https://www.electro-tech-online.com/attachments/chaser-gif.57/

I ran into something interesting and was wondering about this. On the 555 chip pins 2 and 6 I jumped with a wire right over the chip that then goes off to a 2.2 uF cap to ground. If the cap was on the pin 2 side to ground VR1 would not supply a stable timing but when I moved it to the pin 6 side to ground it worked great.

I was wondering how I would go about soldering this now that I am moving to a project board.

Thanks for your help I am very new to this and find it quite enjoyable. I did modify the circuit somewhat and went with Opto's to the triacs. as well as a full bridge rectifier power supply. It works great on the breadboard when the cap was placed on the pin 6 side.

I look forward to finding out why it behaved that way, thanks in advance for you explanations!

Ted

 

[ericgibbs]

hi Ted,
You did the correct change, IMO by using opto couplers for isolation.

The problem sounds like pick up
Is it possible to connect a 100nF [0.1uF] across pins 1 and and 8 of the 555 and do the C2 test again.?

 

[tallan]

Hi Eric,

I will add those caps to it tonight and see how that does and get back to you. Thanks for the quick reply.

Ted

 

[audioguru]

I think the problem is because the contacts on your breadboard are intermittent.
I used a breadboard only one time in my entire electronics career. The contacts were intermittent, the jumper wires picked up interference and the circuit didn't work. I made the circuit soldered on Veroboard and it worked perfectly. I have used Veroboard ever since.

I made many custom-made circuits on Veroboard and the prototype was always sold.

 

[ericgibbs]

To make a decision never to use a project board again, based on one bad experience is very shortsighted, the malfunction was most likely due to poor design or layout in the first place.

If proper care in layout and decoupling is used you will get minimal problems.

I have used for many years and still use project boards to try out circuits of all types, digital and analog.
Over frequency ranges from dc thru 20MHz with no problems.

The only circuits IMO that are not suitable for project boards are very low signal levels, the mV's region, RF signals and mains voltages.