Model Boat Mayhem

Technical, Techniques, Hints, and Tips => The "Black Arts!" ( Electrics & Electronics ) => Topic started by: Tugger on March 18, 2007, 09:44:05 pm

Title: Float Switch
Post by: Tugger on March 18, 2007, 09:44:05 pm
does any one have a design for float switch to activate a bilge pump. After my recent exploits at Balne Moor I think I need one. ???
Title: Re: Float Switch
Post by: norry on March 18, 2007, 09:59:11 pm
   ...Hi Guys...

There is a pressure type switch in a washing machine that could be adapted for a model boat...

My father adapted one a few years ago for a full size fishing boat...

It might be a bit on the big side for "RASCAL" but should fit a lot of the bigger boats...

It might be worth having a look into...But dont be nicking the one out of her indoors current washing machine or it could be an expensive move...

              ...All The Best...Norry...
Title: Re: Float Switch
Post by: Tug on March 18, 2007, 10:03:59 pm
What you are looking for is a mercury switch,  tilt to go

 its a small glass bubble like a LED with a ball of mercury inside to make the contact might need a relay cause they are small,

don't know where I got mine it was so long ago.......
Title: Re: Float Switch
Post by: omra85 on March 18, 2007, 10:21:55 pm
I don't think they're allowed to use mercury nowadays, but I have seen one with a small ball bearing in a sealed tube.
How about a simple microswitch with an extension on the actuating arm, onto which you could fix a cork?? Cork lifts, switch switches, water goes down, cork drops, switch disconnects.
Told you I was simple ;D
Title: Re: Float Switch
Post by: Colin Bishop on March 18, 2007, 10:27:12 pm
Maplins sell several tilt/float switches see:
Title: Re: Float Switch
Post by: bobdoc on March 18, 2007, 10:30:16 pm
Try Hunter Systems:

1) Eco-Pump Switcher: This unit when connected to a pump and a DC power source will sense if water seeps into the Model. The unit will then activate the attached pump and this will empty any ingress of water in the model.

2) Submersible Pump A low cost 6 volt water pump suitable for a wide range of project applications - from automatic watering systems to water jet boats. It is also very compatible with the Eco-Pump Switcher for just pumping water as a Bilge Pump. Size is 60mm high and 30mm dia. Weighs 35g The pump is sealed and can safely be fully immersed in a water reservoir. It is supplied with a length of plastic tube that can be used to direct the flow of water.

Both at

Title: Re: Float Switch
Post by: ministeve on March 18, 2007, 10:59:44 pm
was wiggy there at the washout at Blane if so try and ask him about his bilge pump control box its very good myself and poll have one. i think you can find him on hear or i will ask poll for his number and pm you if there is no probs
Title: Re: Float Switch
Post by: Tugger on March 19, 2007, 01:15:19 pm
Yes he was at Balne we were talking about float switches and asked him for the design. But after my tug turned turtle and the other lost it's prop I forgot about it. so if you could pm his email or ask him to send me details that would be great.
Title: Re: Float Switch
Post by: catengineman on March 19, 2007, 07:31:46 pm
 Maplins do a kit to construct a moisture detector which I am sure could be altered to control a small pump, The only problem I can think of is priming said pump unless it was a good make and had a self priming action. most of the smallpumps I have taken apart have been a simple paddle type but a rubber impeller or even a diaphram choke pump would work

 (I think) don't shoot me if I'm wrong I have some uses!
Title: Re: Float Switch
Post by: Tugger on March 25, 2007, 02:58:43 pm
Have just bought and built a Maplin water detector and hooked it up to a small diaphragm pump from Model Motors Direct and it works perfectly even on 12v. The circuit is very simple two resistors and a Transistor so I am going to build my own version which should cost pennies to make. When I have got it to work I will post details for others to use.
Title: Re: Float Switch
Post by: RickF on March 25, 2007, 03:21:29 pm
Coming in a bit late on this, but wouldn't a car fuel tank switch do the job?. I think they are thermistors (basically a transistor which reacts to temperature - hotter or colder when wet or dry).

 On my car it turns a light on when fuel is low, so you should be able to adapt the circuit to turn a pump on when water is high.

Title: Re: Float Switch
Post by: Doc on March 27, 2007, 05:23:06 am
If you don't mind experimenting a bit, you might try this circuit.  It's very generic and simple.  Hardest part will be finding the corresponding 'UK'/'USA' parts (only 'touchy' one is the SCR).  The majority of the parts are 'dirt' common, nothing special at all except for the 'sensor', sort of.  It's usually made form an etched circuit board, but can be almost anything within reason.  The 'contacts' must be closely spaced, but NOT touching!  The switch(SW) is nice but unhooking the battery does the same thing.  Nothing is to 'scale' so the finished size of the  sensor is variable, whatever works.  Same for the board the other components are on, how ever you happen to assemble them is fine.
 - 'Doc

please excuse the drawing.
Title: Re: Float Switch
Post by: Peterm on March 27, 2007, 09:18:42 am
Doc,   C106 SCR is readily available in UK.   Pete M.
For UK Mayhemers, one source is Maplins Electronics.
Title: Re: Float Switch
Post by: Captain Jack on October 11, 2007, 03:15:39 am
Sorry, came upon this post a bit late, as I am new to the forum, but there is this awesome little item available in the US.
Title: Re: Float Switch
Post by: Umi_Ryuzuki on October 11, 2007, 04:43:43 am
This is the circuit we use in our combat models... O0