DIY Enlarger Timer Circuit?

[ZorkiKat]

Years and years ago, I came across simple electronic schematics for making enlarger timers. I tried looking for these on the 'net, and found one type which is meant for timing exposures for making Dead Link Removed. I don't know if this can be used as an enlarger timer. Anyone else got something different?

Buying a ready made timer may sound practical. However, almost all of the timers I see on eBay are for 110V, which is unsuitable for the 220V standard in use here. I am planning to equip timers for the 4 enlargers in the communal darkroom we recently set up.

 

[largeformat pat]

Have a look on ebay in Australia and UK we use 220-240V

 

[RalphLambrecht]

All of Europe uses 220V.

Since you're in the market anyway, why not consider an f/stop timer?

 

[MPandolfo]

ZorkiKat,

Unless you really enjoy fumbling with circuit boards, integrated circuits, relays, etc. I suggest you buy a ready-made timer. Regarding the costs, you will find that building your own is much more expensive than you think. Displays, switches, buttons, knobs, cables, connectors, box, power supply, and things you don't imagine are the most significant parts of the cost, not so with the "fundamental" parts of the project (SSRs, ICs).

I second Ralph's suggestion of an f/stop timer, they are a lot more comfortable than a simple "seconds" timer.

Regards,

Marcelo

 

[Chan Tran]

Unless you have a special need (a function that isn't available in comercial timer) buying is much better than building. I have build many timers but it's never cost effective.

 

[Nicholas Lindan]

There is a design for a simple, seconds only (no f-stop timing), timer on the Darkroom Automation web site.

The files are in the support section, towards the bottom of the page
http://www.darkroomautomation.com/support/index.htm

(If you downloaded the files before 0:01 06April2010 download the updated schematic pdfs)

 

[steven_e007]

I'm with MPandolfo on this.

I actually do enjoy playing with circuit boards and stuff - and I have learned the following:

1. I only ever complete about 30% of all the DIY gadgets I start.
2. Only about half of those work as well as expected.
3. They always take at least twice as long to perfect as I expect, but sometimes ten times as long or more ^_^

So...I wouldn't go the DIY route unless you are doing it for fun and/or satisfaction or something. If you need working timers in a reasonable time frame - IMHO eBay is your best bet.

 

[kittyhawk88]

DIY F Stop Timer.

I am toying with the idea of a simple f stop timer. If there are those who are interested. I propose designing a simple DIY f stop timer which is open source around a simple pic chip.

Some of my thoughts are :


Simple to use
Always counts up from 0 to 64 seconds.
At start switch enlarger on.
Beep at each major f stop , e.g. 4 seconds 8s, 16 s 32s 64s.
Provison to beep also at 1/4 or 1/3 stops between major periods.
e.g. count up to 8 seconds and beep at each quarter stop.
ability to set range for beeps. - helps with making test strips.
at end of counting period trigger a rely to switch the enlarger off.

I can draw a picture of this simple device. But don't know where to post it.

The target price should be around $25 -$35.

Shoud use a simple 5V USB plug pack or 12 Volts plug pack.

1) Make up kits for those who want to solder them up
2) Make up finished items - small run of 50 units for those who don't wish to bother wiht the above.
3) Offer schematics and board layout to the APUG members and anyone on the web for that matter.
5) Wite up the software to control the timer- offer binary and source code to anyone.
6) Get a repository going for those who want to offer modified code based on the board layout.

I'll definitely go with SMD components onlyto minimise labour..

What do you guys think..

Do you need a simple F stop timer that beeps and lights a red led at each major F stop?

I'll definitely need one to help me wiht my test strips...

Please let me know your thoughts.

 

[Jerevan]

Isn't there some sort of cheap converter/transformer you could plug in to get the 110v timers to be useable at 220v?

 

[Steve Smith]

All of Europe uses 220V.

The UK used to be 240 volts whilst the rest of Europe was 220 volts. All of Europe should now be standardised at 230 volts.


Steve.

 

[tkamiya]

DIY F Stop Timer.
The target price should be around $25 -$35.
I'll definitely go with SMD components onlyto minimise labour..
What do you guys think..

I used to be an avid DIYer. I think your estimate is very far off.... Buying just components will cost you about your target price. Add to that, a simple PCB made by a third party will cost $20 or so in small batches. On top of it, switches, case, tooling, and misc hardware will double all that. In small batches, your cost out the door with no profit will approach $100 if not more.

SMD parts may be cheaper per unit but usually aren't sold in small quantities. Unless you automate the building process, it won't minimize labor but will increase it.

I think, using traditional leaded components with universal PCB and a simple parts kit without switches or case may be possible near your price.

I like your idea but economically, I don't know if it's a good idea. (sorry...)

 

[jp498]

DIY F Stop Timer.

I am toying with the idea of a simple f stop timer. If there are those who are interested. I propose designing a simple DIY f stop timer which is open source around a simple pic chip.

Some of my thoughts are :


Simple to use
Always counts up from 0 to 64 seconds.
At start switch enlarger on.
Beep at each major f stop , e.g. 4 seconds 8s, 16 s 32s 64s.
Provison to beep also at 1/4 or 1/3 stops between major periods.
e.g. count up to 8 seconds and beep at each quarter stop.
ability to set range for beeps. - helps with making test strips.
at end of counting period trigger a rely to switch the enlarger off.

I can draw a picture of this simple device. But don't know where to post it.

The target price should be around $25 -$35.

Shoud use a simple 5V USB plug pack or 12 Volts plug pack.

1) Make up kits for those who want to solder them up
2) Make up finished items - small run of 50 units for those who don't wish to bother wiht the above.
3) Offer schematics and board layout to the APUG members and anyone on the web for that matter.
5) Wite up the software to control the timer- offer binary and source code to anyone.
6) Get a repository going for those who want to offer modified code based on the board layout.

I'll definitely go with SMD components onlyto minimise labour..

What do you guys think..

Do you need a simple F stop timer that beeps and lights a red led at each major F stop?

I'll definitely need one to help me wiht my test strips...

Please let me know your thoughts.

I'd love that, and I do kits, but I don't have the stuff to build SMD style. That combination is usually mutually exclusive. I don't think kits really save money these days, unless it's something that requires the boards to be hand-populated and soldered.

While your feature list appeals to me, you could probably copy an old timer from the 70's 80's and if you had to do a scaled back project. I like some of them, but the switches tend to get corroded or worn out and the caps are probably dried out. It could be redone with modern switching universal voltage power supply, debounced switches, etc..

Only feature I'd add is a dimmer on the display.

Another system with potentially less parts and more off-the-shelf would be a USB controlled relay with a computer program to operate the timing functions. The software should be able to be used with a red gel over the display of a netbook/laptop. If it were network controlled and web app based, it could be managed by a ip[hone,ad] or android or other devices as well.

 

[tkamiya]

Probably the simplest thing we can do is to use something like 2 digit BCD rotary thumb switches for setting up time, one push button for start, pull-up all leads and feed them into input pins of small PIC chip or something. Then take one output pin, use a transistor to drive a relay. The start switch needs to be debounced in software but thumb switch can be read once the start button is pressed.

This way, there is no display issue to worry about, small parts count, and basically duplicate the function of an old Gralab 300 timer.

 

[jp498]

Probably the simplest thing we can do is to use something like 2 digit BCD rotary thumb switches for setting up time, one push button for start, pull-up all leads and feed them into input pins of small PIC chip or something. Then take one output pin, use a transistor to drive a relay. The start switch needs to be debounced in software but thumb switch can be read once the start button is pressed.

This way, there is no display issue to worry about, small parts count, and basically duplicate the function of an old Gralab 300 timer.

I'd want a focus switch as well to turn on/off the enlarger for focusing/composing.

If you have lots of outputs you could have it control the blower for the big enlargers too. Start the blower up with the bulb, then shut if off 2 minutes or whatever is appropriate after the bulb goes out.

 

[ic-racer]

I build a 555 based timer from a Popular Electronics project back in 1974. It cost about $25 in parts back then.


Timer and enlarging exposure meter:

 

[tkamiya]

I'd want a focus switch as well to turn on/off the enlarger for focusing/composing.

Yeah, but you can do that with a simple switch. There is no need to involve cpu or logic with that.

 

[tkamiya]

I build a 555 based timer....

Why would you want to mess with that ANALOG crap...

 

[olleorama]

I build a 555 based timer from a Popular Electronics project back in 1974. It cost about $25 in parts back then.


Timer and enlarging exposure meter:

That's a beauty! I built a NE555 based timer too, but not for photography or darkroom use.

 

[Steve Smith]

My first darkroom timer was a 555 counting seconds into a digital counter which was compared to the input from a couple of BCD thumbwheel switches. When the count and the switch input was equal the circuit would switch off courtesy of a digital comparator.

I still have it somewhere. I will see if I can find it.


Steve.

 

[GeorgesGiralt]

Hello !
You plan to use the timers in a shared darkroom (with possibly child using them).
I would strongly advise to buy a reputable make/model backed up with compliance to various electrical code and the one relevant to your country.
A darkroom is a place where electricity and water share a very tight place. And they don't mix.
So if you make a timer yo MUST ensure no one could be injured by it even by miss use. And you MUST comply with all electrical and safety code ... Quite a job (just to gather the requirements...) !
Last but not least, when it comes to safety avoid buying second hand. You never know if the unit had been tempered or not (unless you have them checked by the manufacturer...)
Hope this helps

 

[GeorgesGiralt]

I forgot to add that you can have a NE555 timer made to progress in geometrical instead of linear. For example you can have times like 1.4, 2.8, 4, 5.6, 8, 11, 16 ... seconds... If you add a switch to divide the basic interval in half it could be useful.

 

[kittyhawk88]

Hi Al thanks for the replies.

I think i am going to go ahead and build one anyway..

HEre are m thought on compliance. That's the reason I would use a simple plug pack for input.

As for the switch gear. I will put all the wiring and tracks in place for those who want to connect an enlarger to it.

As a bsic f stop timer.. it it beeps and flashes at the right moment. I don't think it's that difficult to reach a power switch and hit the on or off switch.

Those who need the automation can go buy a relay, open up the box and solder it in. In fact to sidestep those compliance issues, we can go all the way up to relay. that switches. It's then up to the user to open up and wire it up to the enlarger . I think that should solve the problem. A terminal block will do. I am sure if I put up a web site , there will be plenty of volunteers who will do a "howto wire up enlarger" safely..

This is after all for a hobby.. labour of love...

It can even be powered by 4 AA rechargeables..

Board - I can really roll them off quite inexpensively. I know a PCB manufacturer who does work for large contracts that i dish out. So he can get some done for me mates rates.. another benefit to the community.

I'll get a recalibrate on the cost of components and soldering up and get back to you guys.. Maybe $50.00 at the most .

At what price will you guys buy a Simple F Stop timer ?

$25
$35
$45
$50


Give me a vote please..

 

[kittyhawk88]

Refining the specs as we speak:

Device is battery powered 4 AA's or 5 - 12 Volts DC plug pack (solves those pesky CE C-tick, FCC Part 15 Electrical regulations)

Always counts up from 0 to 64 seconds.
On activation beep 3 times flash led 3 times then start counting up
At 0 seconds trigger 12Volts/Relay switch ( user implemented after purchase) Switched Terminal Block.
Beep at each major f stop , e.g. 4 seconds 8s, 16 s 32s 64s.
Provison to beep also at 1/3 stops between 8 seconds to 64 seconds.
e.g. count up to 8 seconds and beep at each 1/3 stop.
ability to set range for beeps. - helps with making test strips.
at end of counting period trigger 1 long beep and simultaneously trigger the relay to switch the enlarger off. (user to implement)



I can draw a picture of this simple device. But don't know where to post it.

The target price should be around $25 -$35.

Shoud use a simple 5V USB plug pack or 12 Volts plug pack.

1) Make up kits for those who want to solder them up
2) Make up finished items - small run of 50 units for those who don't wish to bother wiht the above.
3) Offer schematics and board layout to the APUG members and anyone on the web for that matter.
5) Wite up the software to control the timer- offer binary and source code to anyone.
6) Get a repository going for those who want to offer modified code based on the board layout.

I'll definitely go with SMD components onlyto minimise labour..

What do you guys think..

Do you need a simple F stop timer that beeps and lights a red led at each major F stop?

I'll definitely need one to help me wiht my test strips...

At what price will you guys buy a Simple F Stop timer ?

$25
$35
$45
$50


Give me a vote please..

Please let me know your thoughts.

I'm going to go to prototype soon, I really need such a timer myself. Will keep you guys posted.

Anybody know how to post photos and schematics on this site ?
Thanks

I'm in sydney for those who need to know.

 

[David Grenet]

Images can be attached to posts - there's a button on the toolbar for it.

Good luck!

p.s. I'd be inclined to include some seven segment LEDs to display the time remaining, and I'd make it count down rather that up, but it's up to you!

Oh, and I'm happy to help troubleshoot for you if you run into any problems...

 

[paul_c5x4]

Refining the specs as we speak:

Always counts up from 0 to 64 seconds.

For lith printing and alt processes, 64 seconds is going to be limiting. I have used exposures of five minutes, and I suspect some are going even longer with UV.