Anyone built a homemade timer?

#1: Post by **Ross Leidy** » October 31st, 2009, 12:32 pm

Given its 1 hour warm up time for its 8 liter boiler, I want to put my Pasquini on a timer. My initial thought was to get the Intermatic HB114C, which is the 20A/220v version I'd need for my machine. But, I can't quite get past the fact that it's only a 24 hour timer. I'd really like to have separate weekday and weekend schedules. I got to thinking that perhaps I could build my own timer out of a digital wall switch (like this) and an SSR (or two). Has anyone done this or comment on whether this sounds like a viable option?

I've never worked with SSRs, so I do have a couple specific questions:

To handle 220v, would I need to use 2 SSRs - one for each hot leg? It seems like one might work, but not be as safe. How about a dual output SSR?
Would heat sinks be recommended?
I'm assuming I'd use SSRs with 110v control voltage if I wire the wall switch with 110v as it's intended to be wired. Low voltage control voltage SSRs are much easier to find on ebay, so maybe the digital wall switch (which has a battery) could be used to just switch low-voltage dc? If so, what's a cheap way to get 12v dc? Of course, a dc power source would probably use 110v ac, so I'm not simplifying things going that way.
Is the control side of an SSR already high impedance, or do I need to stick a resistor in there?

Thanks for any comments or suggestions,
Ross

#2: Post by **Ben Z.** » October 31st, 2009, 1:04 pm

Ross Leidy wrote:I'm assuming I'd use SSRs with 110v control voltage if I wire the wall switch with 110v as it's intended to be wired. Low voltage control voltage SSRs are much easier to find on ebay, so maybe the digital wall switch (which has a battery) could be used to just switch low-voltage dc? If so, what's a cheap way to get 12v dc?

I'm not 100% sure, but I think if you use a cell phone charger or similar you won't need to worry.

#3: Post by **Marshall** » October 31st, 2009, 2:20 pm

It will probably turn into a digital nuisance, if it doesn't have a simple, one-button on-off override.

#4: Post by **Psyd** » October 31st, 2009, 6:47 pm

Ross Leidy wrote: I'd really like to have separate weekday and weekend schedules.

Probably the easiest way to accomplish this, if not the cheapest, is to use one of your already available 110V versions to switch a relay on the 220V circuit.
OTOH, I like mine on 24 hrs. Tea, noodles, oatmeal/cream o'wheat, scrambled eggs, jello or pudding. Instant boiling water has so many apps.
And, I can pull a shot at whim!

#5: Post by **cafeIKE** » October 31st, 2009, 11:23 pm

Use a mechanical reay. No haetsinks required. Assuming tools and requisite knowledge, it's a 30 minute job, AFTER parts are collected.

#6: Post by **yakster** » November 1st, 2009, 1:09 am

You *could* put it on an 20A 220V X-10 module and home automation from your PC to set a schedule. Should be able to override with a wireless remote.

Module here (http://www.x10.com).

There site is a bit annoying with all sorts of flashing screens that makes it look like one big banner ad, but their product works well (though I haven't tried the 220 V modules)

-Chris

November 1st, 2009, 6:02 pm

Thanks, guys - all great suggestions. I think I may start off with Ian's suggestion first because I have a mechanical relay around somewhere (if I can only find it). If I get something up and running, I'll post a followup. Thanks again.

Ross