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555 Timer 0-60

R3=560K
C1=47u
VR1= 1M
I want to know if i have connected the Resistor, cap, trimpot correctly.
The design of this circuits time delay range is 0 - 60 seconds.
It should be 30-60 seconds.
Did i connect something wrong or is this normal?
Does it matter how R and C connect to VR?
 

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i was working with another member on this. He and another member supplied this. I breadboarded it and it worked ok.
I rebuilt it in DesignSpark for the experience. (im new) I added 3 leds. I thought i kept everything the same. thank you for helping spot any issues.
I notice now that R1, R2 and R3 are incorrectly labeled but connected properly
 

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crutschow

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What is the nature of the trigger signals from the "modules"?

What is the purpose of D1?

What exactly, is the circuit supposed to do?
 
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What is the nature of the trigger signals from the "modules"?
a signal from TDB62003A driver on another circuit trips this circuit. (turns on a 12v fan) as long as the signal is (low i believe) the fan remains on. There are up to 8 identical boards that are connected to each of the pins. they all do the same thing. Trip the circuit. When the last signal on the darlington driver goes high the fan remains on for an additional 60 seconds.

D1 is part of the circuit. i did not question its purpose. I had help from 2 members making this.
 

crutschow

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Okay, now that I understand the trigger circuits, I see that D1 keeps R3 from charging C1 when all the trigger inputs are high.
Did i connect something wrong or is this normal?
Does it matter how R and C connect to VR?
Is what normal?
So I see no problem with your connection of the pot, R1, or C1 if that's what you are referring to.
 

Ian Rogers

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All I was worried about was X1 and X2... But as they are caps, I feel better... Btw X1 would be referencing a crystal not a cap..

My only whinge is the size of the PCB tracks... I can see a lot of bounce
 

Ian Rogers

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You have a relay on those tracks.. My ground is normally 60 thick or the entire plane if I can get it..

There is a 555 timer application on this site to achieve the timings you need.. Just check the pinouts of the pot..

Its not listed anymore, but I can still link it in.. IC555 Astable Type1 Timer Calculator V2 Type 1 (electro-tech-online.com)

Looking at Erics astable, the maximimum is 32 secs and the minimum is 0.. The 560 ohm resistor should be with the diode to get what you want
 

AnalogKid

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For something like this I would start with all power traces at 100 mils and all signal traces at 25 mils, and reduce or neck down in tight spots. You're paying for the copper whether or not you use it, and wider definitely is better.

ak
 
All of the design rules in almost all layout software are adjustable
I did increase the rails to 15 on my own but I could just imagine the difficulty id have plotting nets with such large tracks. I spent a great deal of time eliminating all the vias. I did do some reading on track widths and i see there is some what of a formula to the size of the tracks. I do appreciate the information. This is the other circuit connected to this circuit. You can see the prototype in the upper left. Ive got 18 of these to make. 6 in each box with a power supply and one (fan) circuit for each box. it simply cools off the power supply when any of the lighting circuits is tripped.
 

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Ian Rogers

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When you have several inductive loads, the emf gives quite a kick... You have a flywheel diode across your relay but where do you think the "dump" will go?

Your ground rail is sooo long and sooo thin the switching of the 555 will / may be compromised.. You might have to solder extra wire along the ground plane to help it.. The 5v rail will also wobble so a snubber cap across the diode would help. You will soon know as Q1 won't last long..
 

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