Float Cut off Switch for Glass Beaker

[tristen]

Just a quick question:
The Liquid sensor has a black flat surface that (I assume), is to be attached the side of the Flask/Beaker/Vessel.

What can I use to adhere it to the side that won't interfere with the signal?
There are no instructions at all and none of the eBay site. So I'm not sure as to its 'range'.
I will also need to test it on the angled conical flask side and

Just a DOH! moment as I was finishing the post - Double sided tape, should do it?

Today, I'm going to jerry rig it up for a test.

I'd use a small dob of araldite to attach it.

Araldite will adhere to plastic/glass and is virtually transparent.

[GT250]

Ok. Problem
I'm going to cry if I have done a stupid mistake.

Today I tried to just wire up a test setup. Using a desk fan as a replacement still.
When everything was connected the fan didn't turn on!
I bought the SSR as recommended by fandtm666's post in the 1st page, and wired it up as per Onefella's diagram, 2nd page.

The SSR seems to be in a NO state.
I'm using a copper 9vDC @ 300ma PS for the Input source.

The SSR when the DC source is connected shows a Red LED. The Liquid Sensor lights up when my finger passes over it.
I reversed the Input side and no red LED an no Sensor Light.

I know that the 240v input is AC - so I reversed the A to the N - just to see if I wasn't going mad. Made no difference - of course!

I replaced the fan with the actual Still (thinking it might be the draw), that the SSR needs - but nothing…

Don't tell me that I should have bought (even if they exist - as I haven't even checked!), NC SSR's..?

One of those 'Why do I bother' times in my life....

I'm hoping that after buying three of these SSR's I have made real stupid mistake..

[george65]

A bit hard to follow your description but if you are trying to power the fan with 9V@ 300 Ma, I'd say the problem is there isn't enough power to drive the fan.

If the SSR is lighting up, and it should only light up when the level sensor is activated and then go out till you put your finger across it again, the load side must be incorrectly wired.

The other thing is, You know the SSR is a switch Right and you can't power anything from the SSR itself as in the 2 wires coming off the relay. It is an interrupt so the outputs have to go in the middle of one wire from the power source to the load and the other wire goes from the power source to the load directly. You don't hook the 2 output terminals of the SSR to the 2 poles of what you want to drive.

Another problem you may have with the SSR is that it won't shut off or completely shut off. It is sometimes needed to put a Drain resistor across the switching ( low Voltage side) so that when the power goes off, the residual current in the device(s) in depleted allowing the Mosfet in the SSR to completely shut down. This could be a problem in that the level sensor may have an amount of capacitance or leakage and keep the SSR activated.

I looked up the load of the SSR and best as I can find, it should be in the 5 Ma ballpark so plenty of margin for the level sensor to drive it. Also won't take much to keep the thing powered.
The light on the SSR and the Light on the Level sensor should work together.

Just check your wiring REALLY carefully. I know you have but sometimes it can be possible to get a mental block and think you are seeing something you are not or get something in your head you think is right but isn't. All been there but it can be frustrating to find it and demoralising when you do trying to figure out how you looked at it 10 times and didn't see what was in front of you.

Stay with it, all part of the fun of learning.

[GT250]

Hi G65,
Yes all good fun, but bloody frustrating at times …

Have checked my wiring and it looks ok. Happy to be told I've got it wrong
I thought the 9v@300ma didn't have enough kick for the SSR to click in the 240v. Have tried 20v@3A and get the same - nothing - from the SSR.

I have connected the Still as I thought that the fan didn't have the draw. Dead as a Dodo

Photo1 shows the 240v in and out with the RED SSR light on (It glows brighter as the DC input increases). And the Sensor with no light as nothing is 'in its way'.
Second photo shows finger on Sensor (Blue light), and SSR red light is OFF.

It really is as though the SSR is in a OPEN State. Have tried a second SSR, same thing.

I want the SSR in a CLOSED state from cold so the 240v device starts and that when the sensor is activated - THEN - it OPENS (turning OFF the 240v device).

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All good fun

[fandtm666]

connection is

9v

ground to ssr - 4
positive to sensor - sensor to sssr 3

240v
ground to still
positive to ssr 2
ssr 1 to still

[george65]

Forgot the sensor was a 3 wire but changing the configuration around as above should work. If it does not, then a DPDT relay would do what you want. One side will be NC the other NO. When it activates it switches. I keep a load of these things around as they can be very handy little gizmos for switching things.
I have one on my AC unit. When the AC is off a solar inverter feeds to phase 1 of my household Circuits. When the AC in on it feeds phase 3 which is the AC is the only load on and feeds that.

A thought occurred with this setup.....
Are you driving a heater with this circuit on your still? If so, won't the mash continue to boil after the heater is switched off and give you more than the 700Ml you require or have you figured this extra amount in already?

[Onefella]

GT250, from the pictures, you have wired the circuit correctly. So stop worrying about that aspect.

Also from the pictures, it seems the sensor circuit is working and switching the relay. However, the LED on the relay seems to indicate it is working in reverse. Even if it is working in reverse, you should still see the load switching on and off, even if it is the opposite of what you want.

For testing, remove the sensor from the circuit and just use a switch instead. The problem seems to be the relay, not the sensor.

If the load is not switching on with control power applied, use a multimeter to check voltage between Neutral and terminals 1 and 2 of the relay before, then during, relay activation. It could be as simple as you have clamped the wire insulation in the terminal and it isn't making a circuit. I can't see any copper wire at the terminals, so it's a possibility.

As far as the circuit working in reverse, I'm not really sure. The LED on the sensor seems to behave correctly, but the LED on the relay seems inverted.

I did wonder if the polarity of the control circuit may be an issue, but I don't think the sensor would work at all if it was reversed.

[hinekadon]

Just get a 9v battery and put it across the ssr positive to three and neg to 4 the ssr will switch on and the led will lite up

[GT250]

Hi guys,
Sorry for late replies - I work Sundays and just got back in 30mins ago.

First many thanks for all your help, I do appreciate it.

It's all working - but in REVERSE...!!!! Arrgh…! - When the liquid sensor detects, the Light on the SSR goes Red and the sensor light goes Blue, and the Still starts..!!!!!
I want the opposite...!

F666, I followed your wiring description, which has got it working but in reverse, and then I read the post by Onefella: I have to work out who's right etc.

G65 - At this stage I don't want additional switches (unless I have to). The Still is a 'heater'. When the power is cut, it stops the flow/dripping within 60 seconds. So I thought it would be a good idea to have it turn off automatically once it reached the 700ml. (
OneFella, You were correct about the 'Reverse' light on the SSR, and I'm 100% all the connections are fine. As above, the lights work together now.

I've swapped the AC of the still from 1 to 2 and back. No good.

Hinekadon, what would that purpose serve as in now? Are you saying to have a 9v batt 'always' connected to have it working as I want?

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[Onefella]

Uh righto. Had to have a deeper think about the (simple) logic involved. I was describing a circuit that comes on when the water level triggers the sensor. Like a sump-pump. Obviously you want the opposite to happen.

Wouldn't your original circuit do that? The relay was off when the sensor was on, and vice-versa.

[hinekadon]

now once upon a time When god made fairys I had the same problem and i solved it by using a bridge circuit where the relay was across the center of the bridge and the voltage went up and change the polairty of the ssr volts and turned it on the sensor was on one leg ??? maybe uncle fester can come up with the circuit ask him don

[george65]

G65 - At this stage I don't want additional switches (unless I have to).

Wouldn't be an additional switch, it would replace the SSR that you have.

Would make things really easy. You would have it wired on the normally closed side. When the sensor detected the booze it would activate, pull the relay across to the non connected side and the heater would switch off. It would stay that way while ever it detected Liquid.

This would be what you want:



Single Component, very easy to wire up, would take up to up to 2400W load but I wire both contacts together to get a full 20A capacity and share the load across the contacts.

To do what you want, in my very limited knowledge you are going to have to add a transistor or a Mosfet to the input side of the SSR and use that to control it.
The other thing as I think I mentioned would be just to use a Mosfet. Little bit of circuitry involved but still I think better than the SSR in the end as they are just a glorified but some what Limited mosfet with and optocoupler for isolation.


Is there any danger if the level sensor should re activate? If so, then I would add a latching relay setup so once the load switched off, it stayed off unless manually reset. Again this is easy in a Mosfet circuit. I'm just thinking that if the booze evaporated somewhat, the sensor may allow the heater to re fire putting more spirit into the vessel which would then be the tails and it would click off again when the level was back to the set point. The level would look good but the spirit would be what you didn't want. If this happened more than once.....

Might be worth testing the amount of evaporation you could get from the flasks and if there was a way of using a tube or something to virtualy seal the flask from the atmosphere, that would be better. If the spirit is above room temp when it hits the flask, it will also be prone to evaporating. If you left this and came home and saw the spirit was below the 700Ml mark, refiring to bring it up to the level may also be unwise unless you have plenty of margin at the 700Ml point before you hit the tails in the mash.

[GT250]

Hi all,

All I wanted was a Auto Cut off when a fluid level reached a certain height.

This is the Still - watch from 2:00 -
The Still consumes 320W.


Onefella, When the original wiring was done, the RED light on the relay was ON, but no 240ac going to the Still.

Hinekadon, It's early in the morning 4:30 and I haven't got a clue what you said. lol!

George65, There is no 'Mash'. There is only 'wash'. There are no 'tailings'. All that Is in the still is 4ltrs of virtually clear 'wash'.
Evaporation is not a concern as I am using conical flasks (narrow neck with funnel so the actual opening would be about the size of a pea), and I can always set the Sensor to 710ml.

I'm sorry for my lack of knowledge george65, but are you saying that I use 'another' type of relay as the one you linked to, or that I get that one to use in conjunction with the SSR I have?

So, ok people. I've got Two liquid sensors and Three SSR's.

I'm happy to wire in a Mosfet or whatever - of which I'm assuming - to make the SSR be ON and then the sensor TURNS IT OFF...

[george65]

I'm sorry for my lack of knowledge george65, but are you saying that I use 'another' type of relay as the one you linked to,

Yes.

Use the DPDT INSTEAD of the SSR you have atm.
The DPDT can switch on and off as you want where the SSR on it's own can only switch on.

[GT250]

Yes.

Use the DPDT INSTEAD of the SSR you have atm.
The DPDT can switch on and off as you want where the SSR on it's own can only switch on.

I’m at work at the moment. Does Jaycar sell this DPDT switch george65?

If so I can pick one up on the way home. Too late now for me to order off eBay.

And could you or anyone else help with a wiring diagram? I’ve never used one of these and never even seen one.
Thanks,
GT250.

[george65]

yes.



Get a packet of spade connectors or a base as shown in the previous pic to hook it up.

There is plenty of wiring diagrams on the net for these things but they should be able to tell you how to do it in the shop. Make sure you tell them you want it to switch OFF when activated.
It will be on as soon as you power it up.
Given the terminals are all exposed, I would strongly suggest buying a small jiffy box and a switch to put it in. If you AC supply won't fit, buy a small DC transformer or an AC and a bridge rectifier and a cap so you can build it all in. You'll only need a small tranny just to power the relay and sensor. You may also want to wire it up with a 240V plug and socket so all you have to do is plug the thing into the AV and the heater into the female plug coming out the box. I found the cheapest and easiest way to do this is just buy a 2m Extention lead, cut it half and wire the ends accordingly. I buy a lot of those short leads just for that purpose. If I need something to drive decent power then I have to get 2.5mm cable and wire the plugs myself as all those cheap, short leads are 1.5 mm cable. That will be fine for the load you are driving though.

I wire a lot of things I do like thermometers, Light dependent switches, power meters, PWM controllers and sensing relays in their own box so I can keep it all neat and safe and plug in what ever appliance I may want in the future or even combine them .

[Onefella]

Onefella, When the original wiring was done, the RED light on the relay was ON, but no 240ac going to the Still.

Yes, but it now works when the LED is on. Have you re-done the 240V terminal connections since the first time? Might be worth trying version 1 again.

[GT250]

Whew, what a day. Very busy at my work...
Just picked up the 12vcd /240vac DPDT relay and the quick connect base from Jaycar.

Have connected the 'Coil' part 12vcd RED/POS to 5 and the Yellow sensor Wire to 'Coil' 6. When I put my finger over the sensor, the BLUE light of the Sensor comes on.

I'm having trouble (worried!), about supplying the 240v to the other terminals of the Base.

I was going to connect the SUPPLY 240V A to 4 and N to 3 but I have no idea where I would connect the power to the Still?

As a thought: Would A4 be connected to the terminal lower right and N3 be connected to the terminal in line for the NC condition...?

Of course I want the relay in NC [The Still turns ON], and when the Sensor turns Blue, I want the relay to turn OFF the Still.

Do I assume that if the Sensor light goes off, then the Still will then run again until the Sensor goes Blue...?
What is the Yellow tab for that is on a spring - a reset..?


Any help on the wiring would be great thanks people as I can't afford to keep buying these gizmos for trial and error.
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[Onefella]

Modified original diagram, and relay base connections.

[george65]

First of all, there is no trial and error with this gizmo. It WILL do exactly what you want IF you wire it right.
No if's or buts. You can make it switch something ON with the sensor if you change the 240 terminals from one set to the other. You could also put a Light or a buzzer ( 240V) on the NO terminals to tell you when the still had switched off.

It is exactly the same to wire as the SSR for basic operation the way you want.
You put the level sensor on the coil contacts.
You put the still connections across the NC contacts.
When the sensor energises the coil, the still will turn OFF.
You leave the NO contacts un connected unless you want the warning light or what ever to tell you when it's switched off.
The NO terminals will be energised when the still is OFF so don't go putting your fingers near anything.

Do I assume that if the Sensor light goes off, then the Still will then run again until the Sensor goes Blue...?

YES!
Exactly as I tried to caution you about in a previous post.
Before emptying the flask you will need to switch the sensor/ relay off either at the power point or with a switch in a jiffy box as I suggested.

The yellow tab is for mounting the relay on a DIN rail which are used in electrical circuit boards and boxes. Same system used for Breakers, timers and other components used in electrical control boxes and switchboards. You just pull the tab back, hook the base on the din rail, release the tab and it locks it in place.

Try not to over think this. You wire it exactly the same as you had the SSR using the NC terminals on the 240 side of the relay and ignore the other pair. The 12V side goes to the coil terminals which was the low side on the SSR. Just unscrew the wires from one, put them on the other and they should be right.

That's it. very simple and straightforward.