Hey guys its summer here and temperatures rising as high as 43 degree celcius.. coolers are out. i have a simple plan in mind for saving energy and water usd for coolers. ours is a cooler using 60 L of water in 4-5 hrs. and the water is carried on from a lower tub to an upper tub for draining it on to a special grass fixed on the walls. now this requires a pump of 50 watts at least. and it consumes more energy and water if running continuously. so i am thinking of designing a circuit that would switch the pump on for 2-3 min every 15-20 min. at other thimes it would be off. any ideas??

 

A simple 555 circuit connected to a SSR. A wall wart to power the 555, the 555, and the Solid State Relay.

 

True. You can get that much time with a TLC555 chip because their input current is in the pico amp range.

Please forgive me if this is a duplicate. This site got a bit hinky and sent me to "advanced" when I clicked on "post quick reply".

 

Actually 20 min is within a standard 555 range. The problem is always the capacitors, not the timer. If you use new parts most capacitors will work OK, but a lot of electronics hobbyists use junk box parts, which makes it more iffy.

I'm assuming the "other times it will be off" is a simple manual switch. I'll put something up using that assumption, but we need more information.

How does it gets turned off?

What part of the world are you in?

What the pump motor is going to use in the way of voltage/AC/DC?

 

I'm at the hottest part of India. and my cooler works like this. We have a 1300rpm motor for fan and near 100 watts motor for the water pump. the pump carries water from a lower tank to an upper tank and this tank has holes on 3 sides to drain water on the grass pads to cool the air. then the cool air is blown inside the room by a fan from 1300 rpm motor. now this pump consumes much energy and water and also makes the room humid so i want it to be off for 10 min and on for 2 min undefinitely. and one thing more this all works on AC mains 220v at 5 amp supply

 

Why use a timer alone? I would think you would want to use a float switch to ensure there was no over flowing.

The float switch could trigger the timer to pump the lower basin down for two min. then wait for the float signal again.

 

Why use a timer alone? I would think you would want to use a float switch to ensure there was no over flowing.

The float switch could trigger the timer to pump the lower basin down for two min. then wait for the float signal again.

A float is not at all required since we fill the lower tank 2 times a day and just need to control the pump to avoid humidty building up and save some energy and water. if water flows over it continuosly then humidity builds up and colling is vanished. any good ideas? another thing, what is a monostable 555 circuit? does it mean that once the sapn of time is reached it remains on indefinitely?

 

The 555 circuit just turns on and off according to the numbers you gave.

I actually had the numbers up for the components, but lost the thread. I hate it when that happens.

 

OK, I'm going to put up several schematics. The first is the basic 555 circuit you can use to create the on / off for the pump. There are several good ways to do this, this is one.

I'm pulling this schematic out of my cookbook on my blog.

C1 = 1000µF, CR1 can be any diode (for example, a 1N4454, 1N914, or a 1N4001), C2 = 0.1µF,

For 2 minutes on time R1 is 171KΩ (≈ 180KΩ), for 3 minutes on time R1 is 257KΩ (≈ 270KΩ).

For 15 minutes off time R2 is 1.286MΩ (≈ 1.2MΩ), for 20 minutes off time R2 is 1.714MΩ (≈ 1.8MΩ).

The first cycle on/off the off time will be noticeably longer by about 40%. It this is a problem I will add circuitry to eliminate it, it is a basic characteristic of 555 timers.

To turn the pump on you will need either one of these drivers. The 555 will operate between 5V to 18V, so the relay determines what the power supply voltage needs to be.

 

OK, I'm going to put up several schematics. The first is the basic 555 circuit you can use to create the on / off for the pump. There are several good ways to do this, this is one.

I'm pulling this schematic out of my cookbook on my blog.

C1 = 1000µF, CR1 can be any diode (for example, a 1N4454, 1N914, or a 1N4001), C2 = 0.1µF,

For 2 minutes on time R1 is 171KΩ (≈ 180KΩ), for 3 minutes on time R1 is 257KΩ (≈ 270KΩ).

For 15 minutes off time R2 is 1.286MΩ (≈ 1.2MΩ), for 20 minutes off time R2 is 1.714MΩ (≈ 1.8MΩ).

The first cycle on/off the off time will be noticeably longer by about 40%. It this is a problem I will add circuitry to eliminate it, it is a basic characteristic of 555 timers.

To turn the pump on you will need either one of these drivers. The 555 will operate between 5V to 18V, so the relay determines what the power supply voltage needs to be.

i will try it using LED's. can you advice me some good simulation softwares?

 

In working on your problem I discovered a problem with my drawing (that would not affect the operation of the root design). I took the time to correct all my archives.

LTSpice is free and can be downloaded. I do not use SPICE programs myself, I protoboard circuits and use what I know about electronics. My confidence in these circuits is high, but I have not built this exact circuit.

To connect them to a motor I'll show 2 options. Since I don't know if the motor is AC or DC, I'll show both options. SSRs come in AC or DC flavors, my experience is entirely with AC units, which don't handle inductive motor loads very well. However, your application is pretty low wattage, so a decent unit should work pretty well.

R3 is 10KΩ, R4 is 100Ω, Q1 is any decent nMOSFET (Radio Shack sells a IRF510), CR2 is a power diode such as a 1N4001, and you pick the relay to match your power supply.

This is how a SSR would be used. I figure it is an AC unit, but since I don't know what part of the world you're in (which dictates line voltage) I'll leave it there.

 

In working on your problem I discovered a problem with my drawing (that would not affect the operation of the root design). I took the time to correct all my archives.

LTSpice is free and can be downloaded. I do not use SPICE programs myself, I protoboard circuits and use what I know about electronics. My confidence in these circuits is high, but I have not built this exact circuit.

To connect them to a motor I'll show 2 options. Since I don't know if the motor is AC or DC, I'll show both options. SSRs come in AC or DC flavors, my experience is entirely with AC units, which don't handle inductive motor loads very well. However, your application is pretty low wattage, so a decent unit should work pretty well.

R3 is 10KΩ, R4 is 100Ω, Q1 is any decent nMOSFET (Radio Shack sells a IRF510), CR2 is a power diode such as a 1N4001, and you pick the relay to match your power supply.

This is how a SSR would be used. I figure it is an AC unit, but since I don't know what part of the world you're in (which dictates line voltage) I'll leave it there.

I live in india and our supply is 220v 5 amp. for the pump motor, it is AC single phase 100 watts. i have designed a timer and now the problem is with the relay. our local shopkeepers do not give components unless we give them component numbers. even if we take a resistor to them ans ask for the same they ask us the value. so i need guidance for relays. i need at the most 2A for the motor.

My design of the circuit uses a 4060 timed at 3-10 min adjustable with pots. and a 555 timer for 1 min from the output of the 4060. now i intend to use it at 12 volts from a transformer 0-12 rectified and capacitor across the 12 volts dc. it would be 500ma. now i need a transistor mosfet for the protection of my 555 timer like the one you suggested me irf510. the only thing remains is the relay.

 

I have no way to know what parts are in India, though we have a lot of members on this site from that region who might be able to help. 12V relays are pretty common, a 2A version comes in a PCB version from quite a few vendors. I could go to Radio Shack (who is also online) and pick one off the shelf.

You could use one of the many outlets such as Digikey or Mouser and get quite a few part numbers from them.

 

In the Southwest U.S. those are called swamp coolers (evaporate cooling).

The fan motors are typically 1/3 hp for a 3000 cfm cooler and the water pump is typically 1/70 hp.

What function are you trying to place on the timer? The fan or the pump or both?

 

In the Southwest U.S. those are called swamp coolers (evaporate cooling).

The fan motors are typically 1/3 hp for a 3000 cfm cooler and the water pump is typically 1/70 hp.

What function are you trying to place on the timer? The fan or the pump or both?

only pump. fan is to be on continuously. if water runs continuously over the walls then the room becomes humid. i plan to make the walls just wet so that there would not be humidity. also it would save electricity and water.

 

if water runs continuously over the walls then the room becomes humid

You do realize that excessive humidity in the house can be caused by inadequate exhaust and that solution is open doors and windows to increase ventilation.

Those systems were designed to have that amount of water flow. 1/70 HP is small and inexpensive (a little over 10 W).

This project is one where you will be modifying the electrical connections from the Mains and you will be in the presence of water. Not a nice combination by any means.

 

You do realize that excessive humidity in the house can be caused by inadequate exhaust and that solution is open doors and windows to increase ventilation.

Those systems were designed to have that amount of water flow. 1/70 HP is small and inexpensive (a little over 10 W).

This project is one where you will be modifying the electrical connections from the Mains and you will be in the presence of water. Not a nice combination by any means.

the heat is unbearable if any window is open. it has reached 43 degrees now and rises to 48 degrees during may. i am taking this precaution for that temperature. if the window is open then the loss of cold air is more than the heating. it is equal to running just a fan instead of a cooler. my house is a cement brick and gets heated from three sides during day at any time. most of which is from the top. so the room of which window is open gets more heated. i have tried many things and experimented with the timer type working manually for 3-4 days. it worked fine. thats why i am behind this circuit. moreover there is power cut off for 3 hrs anytime during the day so opening the dorrs and windows is no option. we keep a window just open enough to let air pass. how could a 10 watt pump lift water 5 feet high at 10litr per min

 

When I was a kid we used those coolers. Usually they work best at night, and let you sleep. They don't work well, but they are better than nothing.

 

When I was a kid we used those coolers. Usually they work best at night, and let you sleep. They don't work well, but they are better than nothing.

hmm.. thats true. but we have unbearable heat during day and an AC is not a good solution. it is quite costly and consumes more energy. so whatever, we have to modify only these coolers.

 

what size is your swamp cooler?

Normally the water feed in the U.S. is from an tapped outside spigot. The water pressure allows the water to fill the bottom of the swamp cooler.

Attached is a manual for a 3000 cfm model.