1.2 v to opperate a 12v 5a relay

[kace1973]

Hi all

I have a 20 channel programable time that runs on 1.2volt
I am stumped at the moment as i now need to opperate a 12v 5amp relay but dont know how to control the rely from 1.2 volt any help would be great thanks
this project is to tack the sun using a polor mount of a satellite dish

regards Kace

 

[MikeMl]

How much current can the timer output source when its output is high?
How much current can it sink when its output is low?
The signal is high when you want the relay to pull-in?

 

[kace1973]

reply

Hi Mike thanks for the fast reply

the volt out put when hi is 1.2v and 0v when low (off)
as I not sure what the current is i will try and work out a way the link is to the timer
but i have the uk version in 240 vlot I know its not that different once you have the main voltage taken out the timer is the same

the link

**broken link removed**

and this link is to the thread that TCMTECH started about it
I found this little toy at the local Menard's home building supply center today for $3.99. They are Intermatic 300 series 7 day 20 event self powered and self contained digital timers.
Digital Lamp Timer DT300CH | Intermatic, Inc.

Whats interesting is they have very basic power and control circuits that are very easy to modify for different input and output voltages and applications. The power circuit is basically a capacitive coupled line driven to 24 volt DC source that drives a small relay for the actual line voltage output switching.

The actual digital timer is only a three wire system that runs off of a 1.2 volt button cell battery.
This makes the timer itself basically independent of its power source and output systems. All it uses is a simple transistor to switch on the relay with the 1.2 volt signal from the actual timer circuit.

Because the case is split into two pieces and the internal circuitry is split into two independent circuit boards, timer and power, these are probably the simplest and cheapest off the shelf multi function digital timers you will find that can easily be reverse engineered to work on almost any type of timing applications plus still retain the full front face and appearance!

I am planning to modify them work with 20 amp heavy duty relays instead of the cheap 5 amp one they have in them now. They have plenty of internal room and circuit board space for fitting much higher capacity relays or what ever else in them as well!
Or you can just take them apart and stick the face on something else and modify the control circuits to work with your particular power and output needs! The face itself actually has three points that are made for screws to hold them in place so they are about as simple and easy as a person could ask for when modifying an off the shelf item!

this is the link to tcmtech thread
thanks for your help
regards KAce

 

[kace1973]

Hi Mike thanks for the reply

well a good man from this site TCMTECH
wrote this in a thread

subject line
Easy to hack/modify digital timers for $3.99!

I found this little toy at the local Menard's home building supply center today for $3.99. They are Intermatic 300 series 7 day 20 event self powered and self contained digital timers.
Digital Lamp Timer DT300CH | Intermatic, Inc.

Whats interesting is they have very basic power and control circuits that are very easy to modify for different input and output voltages and applications. The power circuit is basically a capacitive coupled line driven to 24 volt DC source that drives a small relay for the actual line voltage output switching.

The actual digital timer is only a three wire system that runs off of a 1.2 volt button cell battery.
This makes the timer itself basically independent of its power source and output systems. All it uses is a simple transistor to switch on the relay with the 1.2 volt signal from the actual timer circuit.

Because the case is split into two pieces and the internal circuitry is split into two independent circuit boards, timer and power, these are probably the simplest and cheapest off the shelf multi function digital timers you will find that can easily be reverse engineered to work on almost any type of timing applications plus still retain the full front face and appearance!

I am planning to modify them work with 20 amp heavy duty relays instead of the cheap 5 amp one they have in them now. They have plenty of internal room and circuit board space for fitting much higher capacity relays or what ever else in them as well!
Or you can just take them apart and stick the face on something else and modify the control circuits to work with your particular power and output needs! The face itself actually has three points that are made for screws to hold them in place so they are about as simple and easy as a person could ask for when modifying an off the shelf item!

end qoute

I dont know if i am able to see how much the current drops as this would be working on a live 240vac and might cause me to hurt my self
if i cant find this out how much of a job would it be to just go with what you think it could be
I dont care if it kills the timer as i did buy quite a few of these


regardsKace

 

[ronsimpson]

The relay in there now has 5A contacts. The timer is made to drive that relay not another.
The most simple way is to get a 240V/20A contact relay with a 220V (or 110v) coil. Have the little relay dirve the big relay.

 

[kace1973]

thanks for the reply

im trying to do away with the 240 volt side as the programmer is housed seperatly from the mains side thats is why i need a solution to run a 12dc relay or smaller as i have about 900 9vdc reed relays

i had thought about just adding a 12vdc transformer but wanted to keep it all solar if poss

regards kAce

 

[MikeMl]

Here is a relay driver that might work for you. Only issue is that the relay is pulled in when the input signal is low, which is likely backwards to what you want.

The X-axis in the plot is the voltage at the CMOS pin. The red trace is the current that the CMOS pin has to sink. The green trace is the voltage at the relay.

 

[ronsimpson]

I do not know about your timer.
My timer does not use a normal relay. There is no power to hold a relay on all day. There is only power to drive the coil for a very short time. They use a latching relay. It is only driven at the turn on or turn off time and not driven in the on or off state.

 

[kace1973]

hi Ron
thanks for the info but i just wanted to use the trigger to activate a relay seperate from the main board and i think i hae it now so i will build it and see

thanks all
regards
kAce

 

[kace1973]

thanks Mike

if that is the case then i just reverse the timer programe to be on all the time then turn off the timer for the duration i want to travel

excellent think problem sorted

Regards kAce
many many thanks
Robert