Camera intervalometer

[Menticol]

Hello!

I've built a timer to trigger my cammera shutter at a fixed intervals. The camera switch was interfaced sucessfuly, and the circuit (done with a 555) worked well.

YouTube - Prueba de Camara 3

Today, I'm building the circuit again, the older one was lost
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I really hate the noobs who ask to get their homework done, but sadly I've converted in one of them because my empirical knowedge isn't enough. If you wanna give me a hand, please:

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I tried changing values of the resistors, and attaching a riridulous ammount of capacitors, but I didn't reached the required intervals. Also tried with potenciometers.

As my potenciometer approach failed, I liked the idea to use a rotary switch and a set of resistors (in place of the 100K resistor shown in the circuit) to set any of this four optional values: 5 min, 10 min, 30 min, one hour.

But I still can't get the correct resistor values, even with a regulated +5V supply, I get random times everytime. I know the 555 IC on this application tends to be inprecise, due temperature and components tolerance, but the random results are unnaceptable.

I admit I'm not using the mathematic formula, just trial-and-error. Or maybe the circuit I'm using (and the way I'm modifing it) is not suitable for the application.

Any feedback would be very appreciated.

PS: I've attached a picture of the old setup, very ugly, the "tape casing" was because I ran out of time before sunrise)

 

[Menticol]

New day, new energy, I've found something:

SOURCE: **broken link removed**

He met the requeriment of the "rotary switch" I desired, but his design only lasts for few seconds, not enough for me

 

[KMoffett]

30 minutes and longer is getting outside of the reliable range for a 555. For a 5 to 30min timer: **broken link removed**

For longer times: **broken link removed**
Ron mentions a timing table that doesn't appear to be on that page, but can be found here. **broken link removed**

Ken

 

[Menticol]

Thank you so much KMoffett! Just what I needed!

It also includes the formula, Timing = 1.1 C1 x R1, very nice.

I'll buy the parts and post the results.

One last question: To make the 7555 energize the relay briefly (then de-energizing it, and start counting again) when time finishes, is enough to connect Pin 4 (reset) to +9V permanently? (like I do with 555)

OR

A single-shot 555 must be added on 7555 output, or another circuit modification is required?

 

[KMoffett]

OOPS! I just realized that the 7555 circuit is a monostable and will not repeat. I'll post a schematic here in a little bit that will work.


The on-time for the relay should be about 1 second.

Ken

 

[Menticol]

Thank you very much KMoffett!! I'll post the project results here

 

[Menticol]

Bad news

I got all the parts, but they didn't have 7555 in stock. I know this will trigger the well known Audioguru's comments about electronic components vs. country development but I admit it, they don't even know what a 7555 is.

What about connecting a group of 555? The fist trigger the second, second triggers the third, so the poor time handling of each one is summed to get the required time?

 

[KMoffett]

LM7555 is just another company's part# for a LM555.

ken

 

[Menticol]

Thank you Ken! yes, they suggested me to use a 555, but the page states

"However you must use the CMOS type 555 timer designated the 7555, a normal 555 timer will not work here due to the resistor values."

What do you think?

 

[KMoffett]

Right you are...forgot what we were doing here. Other CMOS "555" part numbers I've seen: LMC555 LM555C TLC555 TS555C
Don't know if that helps.
Ken

 

[Menticol]

Thank you so much by your time, KMoffett!

Unfortunetly I've arrived too late, stores closed. I'm gonna work with my crappy 555 circuit tonight, just to get some pictures to impress the photographer girl

If the results are decent I'll post the work here too

Tomorrow I'll look for the IC you said

 

[audioguru]

An LM555C is an ordinary 555, not a cmos one.
Why not use an IC timer that has an oscillator and a counter like a CD4060, CD4536 or CD4541?