Simple timing circuit, 3 x 15Hz = 45Hz

[Cobalt60]

Hello everybody. I would like some help on choosing components for a simple timing circuit. I think it is OK to assume a 50% duty cycle. Id like for 3 solenoids to be operated at 15 times per second each, but timed in such a way to provide for a smooth 45 times per second. Also to consider, I believe the solenoids are to be operated on 9 volts.

One way I figure would be to setup a timer for each solenoid at 15 times per second, and somehow get the #2 solenoid to star at exactly 1/45 second after the #1, and get the #3 to start exactly 1/45 second after #2.

Any and all advice would be appreciated. Especially I would like to know what parts to purchase.

Thanks much

-Chris P

 

[colin55]

You will need very special, high speed, solenoids.
Before you do anything, look at the cost of high speed solenoids.
How much "throw" do you want?

The pulsing to these solenoids it simple. It's just the cost of the units that will shock you.

 

[Cobalt60]

I already have the appropriate solenoids. I imagine the circuit to get a single solenoid to operate at 15 times per second is fairly easy, but I have no idea how to get them to operate sequentially for a smooth 45 times per second.

Again thanks for any help

 

[colin55]

Simply connect them to the first three outputs of a 4017 operating at 45Hz from a 555. This will give each a 33% duty cycle.


Colin Mitchell
TALKING ELECTRONICS.com

 

[Cobalt60]

I will give that a try, thank you very much.

-Chris P

 

[crutschow]

Simply connect them to the first three outputs of a 4017 operating at 45Hz from a 555. This will give each a 33% duty cycle.

Not quite. That will give three sequential outputs at a 45Hz rate with a 7 count deadtime while the counter finishes counting to 10.

You need to connect the output of O3 to the MR (Master Reset) input. That will give 3 sequential outputs from O0, O1, and O2 for your solenoids. When O3 goes high on the fourth count, it will reset the counter which forces O0 high and the rest of the outputs low (see function table and timing diagram). Oo stays high for one clock pulse as desired, and the sequence then repeats.

 

[Roff]

Do you mean you want each solenoid to operate at a 50% duty cycle? Can you post a simple timing diagram showing when each solenoid is on and when it is off, relative to each other?

 

[colin55]

You can't have 3 solenoids with 50% duty cycle if you want them to all sequence. They must be 33%.

 

[Pommie]

You can't have 3 solenoids with 50% duty cycle if you want them to all sequence. They must be 33%.

Yes you can, they just have to overlap slightly. Consider a 4017 with the first solenoid activated by outputs 0-2, 2nd solenoid by 2-4 and the 3rd by 4,5 and 0.

Mike.

 

[crutschow]

Three sequential outputs with 50% duty-cycle is a 3-phase signal.

 

[Cobalt60]

Thanks for all of the info everyone. I will try with the 33% duty cycle first and see if that works. But it will be at least a few days because I dont know where to get a 4017 locally.

Also, Im a giant noob when it comes to these simple circuits. So, I dont even know how to set a 555 to 45Hz. Would I also need a 45Hz oscillator?

By day I repair electronics, and I have done some programming, so I can handle this sort of stuff, this is just my first project going from scratch.

Thanks again.

 

[Cobalt60]

Sorry guys I did my own research on the 555 no need to explain that to me.

 

[Cobalt60]

Well maybe I should ask about the 555 here then.

So I got the equation:

f = 1 / ( 0.693 x C (R1 + 2 x R2))

How do I choose a capacitor? The solenoids were pulled from setups that used 10V 6800uf capacitors, but I assume thats just to drive the solenoids and is separate from the function of the ICs. Also, when choosing resistors, would I try to use as low a value resistor as possible?

Thanks again

 

[blueroomelectronics]

Lots of 555 calculators on the web.
**broken link removed**

 

[Cobalt60]

OK well I think I have the 555 figured out. Not sure if I picked standard parts but a 1uf cap, R1 of 1K, and R2 of 20K will yield approximately 35Hz with a 51% duty cycle, which I think is a good starting point.

-Chris P

 

[Cobalt60]

I ordered up all the parts I think I need. I went with a 0.1uF cap, 10k R1, and 200k R2. I'll post a video when Its put together and operational.

 

[colin55]

What buffer transistors are you using and what value base-bias resistors.

What about adding a pot to the 555 to adjust the frequency to exactly 45Hz.

 

[Cobalt60]

First is just the proof of concept. I may add a pot finally, but more than likely will just use several resistors to choose between a select few number of speeds.

What do you mean buffer transistors and value base bias resistors?

 

[colin55]

You need to "drive" the solenoids. What is the current-rating of the solenoids?

 

[Cobalt60]

The solenoids were pulled from setups containing a 10V 6800uF cap. Is this what you mean? Is there any other parts I should be aware of to drive the solenoids? I see there is some sort of 2 pin Ic between the cap and and IC that is already on the board. I plan on re-using those same caps.

Im still not exactly sure how to include those caps in the circuit so any help with that would be appreciated too. I plan on running these off a 9V battery. I just bought 5 4017s so I can fry a couple in my experimentation.

-Chris P