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555 chip information

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cbiblis

New Member
There are so many schematics out there for the different usages of the 555 and alot of terminology for each circuit that i don't know.
I was hoping someone could point me in the right direction for a specific usage.

What i want to do is to build a circuit that will turn power on to a 4v motor for a variable time frame ( maybe a pot adjustment) then turn off for a adjustable time frame the same way. I have a solar tracker that does this.
Thanks
 

MikeMl

Well-Known Member
Most Helpful Member
How long on, how long off?
Do you want to switch the motor positive wire or the motor negative wire?
 

cbiblis

New Member
I probably will switch the positive pole. (Unless it's easier to do the negative, the motor is bi-polar) As for the time frames. i'm not quite sure, hence the variable portion. Until i build your 12v to 4v step down circuit i won't know the timing span. Do i have to set it without variables? I was hoping that i could incorporate pots to vary the time on/off.
 
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MikeMl

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Ok but you have to have some idea. Is it weeks, days, hours, minutes, or seconds????
 
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MikeMl

Well-Known Member
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30 min is too long for a 555. Now it gets more complicated
 

cbiblis

New Member
What i'm trying to accomplish is 24 revolutions per day. That is the perfect setting however i can accomplish that will suit my needs perfectly.
 

MikeMl

Well-Known Member
Most Helpful Member
how about 2 second for 1 minute?

That is better for a 555.

What is the supply voltage (not the motor voltage), but the actual power supply you want to run this on)? I have an idea on how to incorporate the motor voltage reducer at the same time.
 

MikeMl

Well-Known Member
Most Helpful Member
What i'm trying to accomplish is 24 revolutions per day. That is the perfect setting however i can accomplish that will suit my needs perfectly.

24 per day is once per hour, which is way too long for a 555 type timer.

Dont you really want a 1/2 revolution each time? How do you get exactly one/half revolution? Do you have a limit switch or indexing switch?
 

cbiblis

New Member
Ok as it is, the motor at 12v rotates 1 time every 15 seconds @ 4v is rotates 1 round per 45 seconds.
As for the supply power 120v would save me the room on the pcb but 12v supply will suffice. I have more transformers to use, just limited space.
 

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  • motor setup.jpg
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MikeMl

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Ok, now I am totally confused. Do you care where the motor arm stops, or do just want to move a random amount each time you move it?

How far does the motor turn each time the 555 timer's output is ON?
 

cbiblis

New Member
It doesn't matter which position that it stops each time it just has to make 1 full revolution total 24 times a day. So it could move for 1 or 2 seconds then stop for max time. then repeat. the arm makes full rotations. i don't have limit switches on the arm.
 

cbiblis

New Member
rotating 24 times a day would be perfect but it can make more rotations if it has to. Just as little as possible.
 

MikeMl

Well-Known Member
Most Helpful Member
Here is a 555 based timer that runs every 4 min for an adjustable time of 2 to 5 sec. It simultaneously reduces the 12V power supply to an adjustable voltage of 1-10V for the motor.

I guess you could shorten the run time so that it only turns a fraction of a rotation each time it runs. That way, you could reduce the number of complete turns per day.
 

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cbiblis

New Member
Does "rtot" stand for a rheostat?
What does wiper=.8 mean?
What are the Pos,mot- and neg signifying? (I'm confused by what the arrow breaks are.)
So out of curiosity, does the 555, in simple terms, stretch out a wave form? Sort of like a spark plug?
 

Sceadwian

Banned
rtot means Resistance total.
wiper = the resistance value of the wiper?
 

MikeMl

Well-Known Member
Most Helpful Member
It doesn't matter which position that it stops each time it just has to make 1 full revolution total 24 times a day. So it could move for 1 or 2 seconds then stop for max time. then repeat. the arm makes full rotations. i don't have limit switches on the arm.

rtot means Resistance total.
wiper = the resistance value of the wiper?

Right, "Rtot" is the end-to-end resistance of the potentiometer. "Wiper" is the position of the wiper used for simulation. Since this schematic is used as an input to LTSpice, you have to tell it were the pot wiper is positioned. LTSpice lets you make multiple simulation runs with the pot wiper at different positions to see what the adjustment range is, for example.
 
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