Electric water level indicator.

[Jim Holmgren]

I know there are driffent threads on the subject, though most of them seems quite complex especially for one who does not know a lot about electronics.

I want something that will switch on a solonid that will lift the check valve of its seat in the feed water pump, when the water level are at the right level.

Does anyone know how to make sensor like this?
Maybe I can have two electrodes close together and energize one of them, so when the water touch it will pass the current to the other electrode?

/Jim H.

 

[Brian Rupnow]

Buy a cheap, float activated sump pump.

 

[rodw]

This is what you need
https://www.kemo-electronic.de/en/House/Garden/M158-Water-Switch-9-12-V-DC.php
particularly if you are not into electronics.

 

[vederstein]

My boiler uses a spark plug as a water level sensor. The non-pure water closes the circuit and a transistor converts the tiny signal to a higher signal to run a relay. My first implementation of this circuit resulted in a short cycle condition, so I added an off-delay timer.

...Ved.

 

[aka9950202]

That is brilliant! Spark plugs are easy to get and built for much higher pressures and temperatures. I tip my hat to you sir.

Andrew in Melbourne

 

[Jim Holmgren]

Thanks for the advice!

Spark plugs seems like a great idea!

 

[Brian Dickinson]

Hi, Omron do a three probe resistance type float switch which might work for you.

https://www.google.com/search?q=omr...0j69i57j0l4.7766j0j7&sourceid=chrome&ie=UTF-8

Bri

 

[Rudy from Norway]

Jim, Have you tested the circuit on steam? My guess is that the steam, moisture and bubbling inside the boiler will create lower resistance over the plug gap and trigger the circuit before the water level reach it. A drop of water will look like it's submerged. Maybe possible to calibrate though.
If you are into electronics (as I am), I'm thinking the resistance over the spark plug maybe will be high when the water level is low and fluctuating when boiling. However, when fully submerged the resistance will maybe stabilize at a low er level. Then make a circuit to distinguish the stable state to trigger.
A possible catch here is if you are using destilled water, the resistance will be higher even when submerged. Easy to test though.
What about a photo cell at the water gauge glass? Maybe the optical difference when the water reaches the photocell will be possible to pick up? I actually made a sensor similar to this once.
Just my thoughts..
Rudy

 

[vederstein]

Rudy:

The issue you mention is what I meant by my original design short cycling. So I added an off delay timer to fill the water level beyond the sensor level.

The video above was from my prototyping board. In the end I used an Arduino Uno connected to a relay board. I scrapped the transistor because the Arduino already has those electronics included. The Arduino also controls the propane fueled burner, water feed pump, and water inlet valve. The Arduino allows for changes in software to tune the system to my liking. For example, I have logic that prevents the fire from burning unless the water level is high enough. I also have buttons on the control panel to over-ride the logic (like to add more water or force the fire on).

It's not the prettiest solution, but it works. But then my boiler isn't a model in the truest sense, It's just a boiler meant to run my engines somewhat safely.

...Ved.

 

[bluejets]

I know there are driffent threads on the subject, though most of them seems quite complex especially for one who does not know a lot about electronics.

I want something that will switch on a solonid that will lift the check valve of its seat in the feed water pump, when the water level are at the right level.

Does anyone know how to make sensor like this?
Maybe I can have two electrodes close together and energize one of them, so when the water touch it will pass the current to the other electrode?

/Jim H.

Why not use a normal everyday float switch.
Simple and virtually trouble free and no batteries required.
Example below.

https://www.ebay.com.au/itm/Liquid-...36e5ca14b343a2ba83020951a5a8ce&frcectupt=true

 

[DickG]

An electronic boiler water level unit is very simple to make - even if you have no electronic knowledge. Hundreds of them are in use over here in 16mm and G1 steam locos. There are versions for one or two electrodes and the electrodes are quite straightforward turning exercises.
DickG

 

[dbs88]

An electronic boiler water level unit is very simple to make - even if you have no electronic knowledge. Hundreds of them are in use over here in 16mm and G1 steam locos. There are versions for one or two electrodes and the electrodes are quite straightforward turning exercises.
DickG

Hi Dick please could you forward a link to the sensors used in the locos many thanks, I would like to add a system to my marine boiler

 

[dbs88]

My boiler uses a spark plug as a water level sensor. The non-pure water closes the circuit and a transistor converts the tiny signal to a higher signal to run a relay. My first implementation of this circuit resulted in a short cycle condition, so I added an off-delay timer.

...Ved.

Love this idea and would like to add something along these lines to automatically fill the boiler on my steam tug, any help you can offer will be greatly appreciated.

 

[fcheslop]

Use a Schmit trigger and a 555 chip to stop bounce
A dual packaged timer chip 556? could be configured to drive an rc servo to operate a bypass valve
Malcolm Beak had a design published in Model Boats magazine. He is approachable gentleman and can be found on Paddleducks forum or Modelboat mayhem
The write up is in the download section of Paddleducks forum
https://howtomechatronics.com/how-it-works/electrical-engineering/schmitt-trigger/

 

[dbs88]

Use a Schmit trigger and a 555 chip to stop bounce
A dual packaged timer chip 556? could be configured to drive an rc servo to operate a bypass valve
Malcolm Beak had a design published in Model Boats magazine. He is approachable gentleman and can be found on Paddleducks forum or Modelboat mayhem
The write up is in the download section of Paddleducks forum
https://howtomechatronics.com/how-it-works/electrical-engineering/schmitt-trigger/

Thank you for the links, thats very kind, I will follow them up and I look forward to reading Malcolms article

 

[fcheslop]

I think Malcoms design had an update or a mod just cannot remember
If you look on Paddleducks Malcolm replied to a problem a member had building the unit
I made his unit and it worked reliably .This was all pre interwebby we used to have a correspondence circle via snailmail
Malcolms MB22 engine and its boilers are very good runners and punch above there weight


kind regards
frazer

 

[Mechanicboy]

Automatic boiler water level control system with phototransistor.
See at this link https://www.modelboats.co.uk/forums/postings.asp?th=119786

 

[dbs88]

I think Malcoms design had an update or a mod just cannot remember
If you look on Paddleducks Malcolm replied to a problem a member had building the unit
I made his unit and it worked reliably .This was all pre interwebby we used to have a correspondence circle via snailmail
Malcolms MB22 engine and its boilers are very good runners and punch above there weight


kind regards
frazer

Frazer, many thanks for getting back to me. I am very interested to hear about Malcolms Engines and Boilers as I have not yet got engines for my new boat, I do however have a boiler to experiment with. I have tried to download Malcolms article but not succeeded, are you able to upload it? It would be good to hear your experiences of using Malcolms control unit.. kind Regards Dave

 

[dbs88]

Automatic boiler water level control system with phototransistor.
See at this link https://www.modelboats.co.uk/forums/postings.asp?th=119786

Jens, thank you so much that looks fantastic. I really y do appreciate you taking the time to reply. Do you still use the system as shown or have you continued to develop it?

 

[fcheslop]

I built Malcoms level control and his attenuator valve for a 24 hour running competition in the late 1990s at that time we both were building Vic Smeeds River Queen although I designed my own V twin wobbler and a center flue boiler.Malcolm designed the MB22 and it is a far better runner than my little wobbler but lacked reverse unless you fit a gearbox
The level control worked reliably and kept the boiler running for around 14 hours until a pump problem ended playtime
The electronics were easy enough to do but I do remember some mod or other and had to substitute the transistors. I simply dont know if the components are still available now but I would imagine an OP Amp could easily be used.My electronics knowledge is about 20 years out of date.
The MB22 is 3/8 bore and stroke double acting and its easy to build although I would alter the cross head arrangement just my preference. I designed my own pump for it using a scotch crank eventually its going into a Thames Launch kit Iv got in stock.A first for me as I normally scratch build so a learning curve how to glue bits to the pre made hull
I also redesigned Malcolms valves along the lines of gauge 1 practice
Im going to build Vic Smeeds River Princess this year and just starting to gather bits n bobs for it.The engine will a single double acting piston valve with self starting feature and after experimenting using plumbers endfeed T fitting the boiler will be made from a 2 1/4 fitting.The reason for using the T is to get greater boiler capacity on a compact unit as per my Cracker T horizontal
I have sent you a pm
You can see the Cracker in this wee video

kind regards
frazer