Circuit timers for electro etching?

[Ben Dono]

G'day everyone!
I was hoping someone can push me in the right direction.

I'm doing a lot of electro etching logos and designs into steel at the moment and I'm needing a time counter in seconds so I can get an even etch over a large area. Each section gets anywhere from 45seconds to 75seconds in 5 second bursts.

My problem is the process is very manual and prone to time errors. Often I stop everything to clean the etch area etc.. The total closed circuit time I want to be able to monitor not the open circuit time.

Currently I'm just counting '5 hippo's' and would not mind something a little more accurate.

The only solution I have come up with is to wire in an old analogue clock into the circuit.

I would much rather a resettable digital time counter in seconds... Anyone know what it's called or where I can find one? Googled it (closed circuit timers etc.) but only came up with programmable timers not closed circuit counters.

[BobL]

This looks like a job for a small Arduino setup.

[Ben Dono]

I was thinking the same Bob but have been avoiding using arduino's up until this point. The physical side of them looks pretty much plug and play but the code work looks like a nightmare.

[BobL]

I was thinking the same Bob but have been avoiding using arduino's up until this point. The physical side of them looks pretty much plug and play but the code work looks like a nightmare.

Yes, can be very tricky. I've only really dabbled with a bit of the code and usually just ask my son to do things for me.
Chances are someone has already done this or something similar - tracking down if this is the case is also tricky.
I'll keep my eye open.

[Ben Dono]

I might have a quick look myself... I did not think to see if anyone else has written the code. I would palm it off to my son but he is on 3 and liable to just put food on it!

Thanks Bob! Always good advice mate.

[Ben Dono]

Actually I found something that might work. An arduino based stopwatch. The electro etch circuit is just 9-12v DC. I could wire in a relay into that circuit so it closes automatically when I'm etching. Then change to stopwatch arduino code to accept the momentary signal from the relay?....maybe

[malb]

I used be be involved with radio control models generally with Nicads for the radio gear. Standard procedure with the battery packs was to "cycle" them regularly, i.e charge them fully then discharge at a controlled current to the packs nominal 'flat' voltage, and time the discharge cycle and keep comparative data to predict when a pack was deteriorating. A lot of the units that where available relied on using a $12 (then) digital stopwatch modified to have an external contact replicating the start switch and stop switch. These units had a separate reset switch, so could accumulate time over numerous start stop sequences if you wished.
If you could find a similar unit (ebay or Jaycar maybe) its about 10 minutes work to add three wires to give the remote start/stop functionality if you don't want to go the arduino route. Then use a multipole relay as you previously suggested to control the stopwatch and the etch current simultaneously.

[BobL]

What about this?

http://www.altronics.com.au/p/k6145-remote-control-digital-timer-kit/
It has trigger inputs and a relay output.

[ubute]

Have a look at programmable relays or programmable timers, should be able to find one on the cheap to suit.

[Malibu]

Are you looking for a cyclic timer? ie: Power on for 5 seconds, off for 10 seconds, on for 5, off for 10... etc, etc, etc...
You might try one of the Omron HC3R range of timers. I recently fitted one to a mates EDM machine to do pretty much what you've suggested. He says it works brilliantly.

They're pretty pricey though, that's the biggest problem.

[Ben Dono]

Actually Malibu that is on the money in the future when I start doing tank ( immerse the whole part) electro etching. At the moment it's very much a manual operation hold for a five count, stop and move the pad, hold for 5, move the pad, clean the etch site etc...so I'm after a total etch time per section

Going to have a crack at Malb's solution and throw in a relay... when I find the stopwatch! I normally know where everything is in my workshop..don't know what happened to it.

Thanks for the advise everyone!
As always, it's very much appreciated.

[BobL]

Are you looking for a cyclic timer? ie: Power on for 5 seconds, off for 10 seconds, on for 5, off for 10... etc, etc, etc...
You might try one of the Omron HC3R range of timers. I recently fitted one to a mates EDM machine to do pretty much what you've suggested. He says it works brilliantly.

They're pretty pricey though, that's the biggest problem.

I used these timers as a "delay off" controllers for my DC, and my compressor enclosure cooling fan circuit.
I found the timers in a skip inside an air-con control box. They were pretty grubby with rusted connectors but the stubbed up just fine.

I then looked to use more of them but as Maibu says the prices are a bit much for DIY use.

However, have since found a super cheap source at Aliexpress where there's all sorts of Omron (clone?) timers the for ~ $10.

[rrobor]

A timer circuit is the simplest electronic circuit there is. You can get a 555 chip for 30 cents and with another 30 cents of parts create a timer pulsing between microseconds to hours. You could then use that to power a FET which could switch on a relay or ring your bell. Don't know what you mean by closed circuit timer, think that is why you have issues finding something. Timers work electronics, nothing can work open ended. In electronics to create change you have to do data in bytes of information , that is done by a timer so timer circuits are as common as muck. Jaycar probably has an off the shelf kit. Rob

[Yanis]

Here are some examples from ebay.

AC 220V 25A Programmable Electronic Timer Switch DW | eBay (http://www.ebay.com.au/itm/AC-220V-25A-Programmable-Electronic-Timer-Switch-DW-/291794782881?hash=item43f0530aa1:g:BDoAAOSwmtJXY4zJ)

1X 12V Digital Time Switch Electronic Timer LCD Display Power Relay Programmable | eBay (http://www.ebay.com.au/itm/1x-12V-Digital-Time-Switch-Electronic-Timer-LCD-Display-Power-Relay-Programmable-/281400118696?hash=item4184c10da8:g:Fo0AAOSwiLdWAHhh)

John

[Bob Willson]

Or you can get any number of similar things from China for about $5

Shop digital timer with relay online Gallery - Buy digital timer with relay for unbeatable low prices on AliExpress.com (http://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20160706195141&SearchText=digital+timer+with+relay)