A simple counter circuit needed

Jacob J

Joined Jun 18, 2009
159
Hello all

On my boat I have a bilge pump that automaticly turns on, when there is too much water in the boat. I would like to make or buy (cheap) a device that counts how many times the pump has started. What kind of circuit would you suggest for this?

/Jacob

elec_mech

Joined Nov 12, 2008
1,500
There are a number of ways to do this, it all depends on how much effort you want to put into it.

Before delving too far into this, a boat, while not technically an automobile, is a large vehicle of sorts and hence this topic may fall under the automotive topic restrictions section of this site found in the TOS: http://www.allaboutcircuits.com/l_tos.html.

I'll wait for one of the moderators to approve or disapprove this post before proceeding.

Jacob J

Joined Jun 18, 2009
159
I have found this 12 stage binary counter DIP 16 chip.

74HCT4040 http://www.nxp.com/documents/data_sheet/74HC_HCT4040.pdf

If I connect this chips CP (input) to the positive on my bilge pump (with a resistor) so I get down to 4-5volts and then the put a 4,5 volt batterys positive to pin 16 wich is Vcc and ground of the battery to pin 8 wouldnt it work just as simple as that? And then put a push-release button from 4,5 volts onto the MR pin, then I could clear the chip. Then I could put LED's to the first 4 Q's (outputs) and it would then be able to show 15 counts in total?

I don't know if it is okay to tap onto the positive from the bilge pump like I say. Any comments on that?

/Jacob

PS: I am sorry if I posted it in the wrong sections.

Georacer

Joined Nov 25, 2009
5,181
Boat topics have been discussed before in AAC, in the latest revision of ToS. The thread is open for now.

SgtWookie

Joined Jul 17, 2007
22,210

Jacob J

Joined Jun 18, 2009
159
The pedometer approch sounds very simple. I think thats the way I wanna go. I just need to find a cheap one somewhere.

Can you tell me a little more about a reed switch. I have read about it and its a switch that closed by a magnetic field. One thing I didnt understand was about the wire around the switch. Would that be the wire of the bilge pump? Is that enough for the switch to close?

SgtWookie

Joined Jul 17, 2007
22,210
It would take many turns of wire to produce enough of a field to close the reed switch.

How much current does your bilge pump use? That will determine what gauge wire will need to be used.

It would be difficult to wind wire on a reed switch itself. It will be much easier to take something like a Bic pen, chuck it in an electric drill, and just crank on the wire; then trim the pen barrel to suit. If you wanted to get fancy, you could use brass tubing. A drill shank a bit larger than the reed switch body could also be used; you'd have to be careful when removing the coil though.

Jacob J

Joined Jun 18, 2009
159
The pump uses 1.6Amps when running. The wire around the reed switch is the wire that is connected to the bilge pump right? Wouldnt it be easier to tap into the wire-to-wire connectors, that runs from the bilge pump and up to the battery?

SgtWookie

Joined Jul 17, 2007
22,210
The pump uses 1.6Amps when running.
OK, that's what I needed to know.

The wire around the reed switch is the wire that is connected to the bilge pump right?
Yes, in series with it.

Wouldnt it be easier to tap into the wire-to-wire connectors, that runs from the bilge pump and up to the battery?
If you want to go that way, you could use something like this:
It's a reed relay switch with a 12v coil.

The idea is to use the least amount of power from your battery as possible. There will be a minimal amount of loss in the winding around the reed switch, but it won't be terribly significant. However, it might just be more expeditious to use the reed relay with a cap in series to stop the current flow; and use a diode to allow the cap to discharge without energizing the relay again.

Jacob J

Joined Jun 18, 2009
159
Okay, I think I will look into the reed relay a bit more and see if that would do the trick. Thank you all very much for the answers!

wayneh

Joined Sep 9, 2010
16,114
Just FYI, you may already own some reed switches. They're used to sense bicycle wheel rotations, for the speedometer, and they're also used to sense door and window openings for home security systems.