DIY Auto Top Up Device

[Zappy Kiwi]

Hi all,

I will like to share my DIY project, Auto Top Up device. I hope this thread will help all those who would like to have an auto top-top, but do not wish to purchase one off the shelf (too ex?), or would just want to get your hands dirty and DIY one yourself.

The most important components in an auto top up device is the water-level sensor(obvious ). Here, I choose to use a float switch, which is simple to use. However, I will not be using a sucker to stick to the wall of the sump. Instead, I will DIY a float switch holder, using arcylicf which will not drop or slip, which will jeopardise the position of the water-level sensor.

My budget for the Auto Top Up device is $100. Let's begin.....

First, the circuit diagram. Shown below is the simplest design for an auto-top up using a single float switch, DC adaptor (either 5V,9V or 12V), a relay switch (Single Pole Single Throw). The design is self-explanatory from the diagram. The float switch is NC (normally closed, means when float is down, it closes the circult).

Note that there are three types of float switches, NC, NO (normally open) and CV (change over). For more info, read these websites:

Relay - Wikipedia

Madison: Float Switch Technology

[Zappy Kiwi]

The circuit shown above is very easy to build and place inside a small box. However, it lacks many many safetly features. How about including another float switch to limit the max height? In case that float switch A fails to open when water rises above it (ie float jam??), u dun want your pump to operate infinitely and 'top-up water to ur floor too rt? There's actually a simple solution: use another float switch (normally closed type).

How about adding another device to sound off to indicate the the max water level has been reached?? This is to aware the ppl around that it's time to service the bottom float switch?

How about adding a fuse to make the auto top up device complete? How about some nice LEDs to notify that it is functioning properly? How about a switch to manual turn ON the pump?

All the above is included in my proposed auto top up device. See the new circuit diagram attached! More challenging to build also...

Note that I have chosen to use a 12V adaptor and a corresponding 12V relay switch. The relay switch is of Double Pole Double Throw type, so that I can use it to control the green LED to signal 'pump is on'. Also, a simple circuit is proposed for the alarm buzzer device, making use of a readily available transistor(BJT npn) 2N3904. (Actually, this circuit can be omitted if the float switch B is of the change-over type.)

Next up, I will post the shopping list of components, pics, and prices....

[giantbicycle]

Very knowledgable indeed....

[nec]

PowerMan Keep it up

[Zappy Kiwi]

Hi all,

This DIY Auto Top Up Device was completed last year. It is running 24HRS/7days a week till now. I didn't continue to post in the thread that time as I was busy with work. Here's the rest of project story.....

Let me continue by posting the list of materials to purchase. The price listed is at the time I purchase them, which is about 1 year ago :

1) Float Switch** Quantity:2 Price: $38.85

** See posted image

2) 12V adaptor Price: $12

3) 240V/12V DPDT relay switch Price: $12~$15 (can't remember the exact price)

packaging of the relay switch looks like an ice cube.

4) Base connector for the relay switch Price: $5~$8.

Note that this item isn't necessary. I purchase it but didn't use it in the end. Only for testing purposes.

5) Fuse holder and 2.5A fuse Price: ~$2

6) 12V switch with LED Price: ~$3

This is used to manually turn on the water-top up device.

7) 250V switch Price: ~$1.50

Master On/Off switch

8) 2m wires (thick, thin) Price: ??

thicker wires are for 240V ac, thin wire are for 12V dc.

9) wire wrap insulators (big and small) Price: ??

10) 2 pin/strip socket Quantity:2 Price:~$5

to be used for the pump socket, and the 12V adaptor.

11) transistor NPN 2N3904 Price: $0.50

12) connector tab Price: $0.80

13) buzzer Price: ~$1.50

14) resistors Price: ~$0.10 each

47kohms, 500ohms (for normal LED). 470ohms (for superbright LED) X2, 1kohm.

15) LED

5mm red (super bright) $0.50

5mm green (super bright) $1.20

5mm yellow $0.40

16) Box 130mmX90mmX40mm $4

For me, I want to have the box as small as possible. So I choose this. Not that the size of the box depends a lot on the size of the 12V adaptor you manage to buy. The big items are: 12V adaptor, 240V/12V relay switch, 2pin/strip socket, fuse holder. Better to buy the other stuffs first before deciding on the size of the box.

17) crimp terminals for the 240/12V relay switch Quatity: at least 6. Price:~$0.50 each

Total cost I spent is $80~$100. This price does not include the pump. Note that a new set costs ~$150 (from dr evil) with pump with the same features (2 float switches, LED, manual turn-on, fuse etc) . However, you will derive great satisfaction from the completion of this project. I would recommend that you finish reading the post before committing to the project.

Other items necessary:

1) soldering kit (use to burn holes in the box to place the switch, LED, etc. Will be even better if you have a hot knife)

2) crimping plier

Except for item 1, float switch, the rest of the materials you can get from Sim Lim Tower (the shops at the basement). For Item 1, I purchase from Farnell.

I think one of the shops at sim lim tower basement (#B1-37B) sells the float switch for $18~$20. But it is NC, NO type only. For that price, might as well buy from Farnell.

[Zappy Kiwi]

To search for the float switch at the Farnell website, type in 'float search' at the product search. Alternatively, you may want to buy the same types that I have used in my project.

I have attached a scan of my farnell payment slip. I have ordered the parts and ask them to deliver to NTU when I was a student there. I was entitled to 8% discount off the price. Note that you can request Farnell to deliver the parts to your home as well.

Note that I have purchased 2 different types of float switch to save on the cost. The cheaper one is the white colour float switch in the picture. It is of the Normally Closed (NC) type. The connecting wires are also shorter (30cm only), and you may need to use spare wires to lengthen it. I have used this as the top float switch in my project.

The more expensive one is the black colour float switch in the picture. It is of the change-over type. The connecting wires is 1m long. The wires are also thicker. I have used this as the bottom float switch in my project, as this float switch looks more durable.

Both switches are working fine up to now. If you want to save on the cost, you may consider buying only the cheaper type.

[Zappy Kiwi]

The pictures of the items. The plug housing/socket/crimp terminals are optional. I fitted them onto the float switch wires. This is so that I don't have to open up the entire case and redo the wiring if I want to replace the float switch.

The crimp terminals are for the pins of the relay switch (6 pcs), and for the pins of the socket housing for the pump (2 pcs).

As for the pins of the 250V switch, fuse holder, 12V switch, matching socket for the adaptor, I used soldering to fixed the wires onto the pins.

[KenYeo]

Power

[nakazoru]

Hi Zappy Kiwi;

It is not going to be cheaper and easier if we buy a NC for the upper float switch and NO for the lower switch. All connected to the AC mains.

If electrical leak is a concern, buy a earth probe and ELCB of our house will provide safety...

[Alex1503]

There is some mistake in diagram. There is shot circuit when switch 1 is on. How to solve this problem?

Check please.

Thank you

[Alex1503]

I think that adding of a top up container low level sensor can be good idea.

How it can be done?