Cheap 1 hour timer for 220v suggestions

[snowman]

Hi folks,

I need a timer circuit to light a 220v small bulb for 15 minutes on every 1 hour. duration does not need to be accurate. instead of 15 minutes it can be 20 etc.

I looked into 555 solutions, arduino solutions, 4060 solutions. Looks like 220v-12v or 220v-5v adapter is more expensive than circuit itself.

I had problem with 555 solution because every online 555 calculator calculates frequency and period from given capacitor and resistance values, but I need it backwards. a calculator that gives resistor and capacitor values from given frequency. Also they are not clear about on-off times. If I needed square ware that would be fine but that's no the case.

I need ideas about power supply of this device. It should be small and should not generate heat. Needed current is very small, relay is small one like arduino relay modules. There are transformerless power supply schematics online but they don't mention about heat (this device will be in closed box forever)

Basically I could not decide.

Can anyone point me a direction with ideas please.

best.

[Sideshow Bob]

This is not meant to be disrespectful. But this is in the same alley as building your own heatsink using scrap metal plates in order to save money. Programable digital timers that you put into the mains socket are dirt cheap and they often do have a battery for backup. Non digital like this one as an example https://www.ebay.com/itm/Digital-Electronic-EU-US-UK-AU-Plug-in-Programmable-24-Hour-Timer-Switch-Socket/322553113078 is even cheaper. Look for them on EBAY, Alibaba Express etc

[CocaCola]

As Sideshow said, don't re-invent the wheel unless you need to...

Not a product endorsement, just another example of how cheap these things can be sourced vs built...

https://www.ebay.com/itm/Cycle-Delay-Timing-Timer-Relay-Switch-Turn-ON-OFF-Module-AC-110V-120V-220V-230V/263430643827

[Wizpic]

I would use and Arduino mini a 5v relay module all cheap enough from e-bay and one of these for for the power supply 240v to 5v dc all in one no need for rectifier
[urlhttps://uk.rs-online.com/web/p/pcb-transformers/8695025/][/url]

I did a fish tank pump controller the same way it ran left pump for 5 minutes and then the right wave pump plus added a button to turn them off for 15 minutes while feeding work very well

[snowman]

Hi,
To answer Slideshow Bob, I have one of these. Their interval not suits my needs. Also I have one of electronic ones. they cannot turn on and off 1 hour/15 minutes intervals. Mechanical ones work half an hour/half an hour.

To Wizpic; the product you offer is 11 pounds. Not acceptable for me. Aliexpress has cheaper ones but still expensive comparing to timer device itself.

CocaCola got the point. the device he offers is about 5 dollars. I believe including power supply. That was what I needed. I could not find that kind of product with my research, maybe because ebay is not usable in the damn country I live.

thanks.

[Sideshow Bob]

Hi,
To answer Slideshow Bob, I have one of these. Their interval not suits my needs. Also I have one of electronic ones. they cannot turn on and off 1 hour/15 minutes intervals. Mechanical ones work half an hour/half an hour.

Actually those digital week timers are just made for such a task. Once I did a setup very simlar to your project. I had to run a pump regulary  monday to friday but it could not run dry. As that would damage the pump. So I set a digital week timer run for 10 minutes every hour monday to friday. For that job I found a chap timer with 96 programable on/off. More than enough to do the task 

[Parmin]

If you have to make one yourself, I suggest to see Microchip's transformerless power supply and design with a PIC - you will end up with a lot less components and quite cheap system.
OTOH, like most above, I would suggest to use commercially available system.

[Wizpic]

Cheap and custom designs do not go together  , If I was you I would stick with the commercially available system  . You could use  transformerless power supply but then safety come into mind, I looked down this route but then decided against for that reason, I value my house 

[Sideshow Bob]

If you have to make one yourself, I suggest to see Microchip's transformerless power supply and design with a PIC - you will end up with a lot less components and quite cheap system.
OTOH, like most above, I would suggest to use commercially available system.

If on a budget, I would have asked around if sombody could donate an old cellphone charger. As this solution is more safe for the hobbyist. At least if a an orginal charger is used. The aftermarked ones should in theory also be safe. But many of those are cheap products from China, not complying with regulations even if they are labled as such

[snowman]

As I said before I have mechanical programmable timer plug. My intention was remove the internals and insert a power supply, pic, 555 or arduino nano or maybe esp8266 and a small 5v relay. This device have great compact 2 way plug. I also have a koogeek plug and case is so small and compact that I wonder how they fit all electronics there. Power supply, mcu, bluetooth, wifi, relay, leds... But its too far expensive for disassembling.

[ero]

The cheapest system is to use one microcontroller with a relay powered by simple (unisolated) power supply.
It is very easy to make this but the main problem is to microcontroller. You need to program it by using a programmer.

Project files are enclosed.
When yo give the power to the system it is counting first one hour. Later drive the relay for 15 min than close the relay and counting again one hour and continuing so on.

If you are not able to work with un isolated circuit do not make this project it canbe dangerous. If you want a safety system you should use 3w / 0-6V transformer for power supply

Ete

[token0]

I bought dirt cheap multizone timer with clock for my fridge, so it works only when electricity is cheap. It costed about $7 in local Auchan. Clock deviation is about 15 minutes per year

[solutions]

How many of these are you making?

[snowman]

I need 3 or 4. Still I could not find a cheap easy solution. Currently I'm using mechanical 200v timer with minimum on/off rate is 30 minutes. I bought couple of arduino from aliexpress, they arrived but 220v-5v conversion is also a problem because adapters are not cheap. I need transformerless solution but yet... no luck.

[kreutz]

Perhaps this data sheet will provide some ideas to solve your problem: https://www.diodes.com/assets/Datasheets/PT8A2516.pdf

[snowman]

holly cow....

this is what I need..... I can't thank you enough. Datasheet also has transformerless power supply schematic...

You're the man. Thank you my friend... After posting this message I'm going to my workshop... thanks..

Posted on: August 18, 2018, 01:42:17 13:42 - Automerged
aha... PT8A2516 is obsolete product. its end of life. I'm looking for replacement version.

but schematic was great..