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TerraMex · 05-02-2003, 02:09 PM

>Also, I can probably reduce the intensity of the beam enough
>that it won't penetrate water that is mixed with some sort of
>semi-opaque substance.

@Jsimmons

You dont need that many emitters/receivers. 4 or 5 will do. But you need to plant them in the opposite wall, at the same level. When the level drops, the IR beam gets across, and triggers the receiver. That with a opaq liquid.

http://clientes.netvisao.pt/carlo001/procooling/13.jpg , like this.

You can use different approaches to the same type of measure with light. You can use a powerfull light on top of the res and use an LDR cell on the bottom of the res. As the level drops, more light gets to the bottom and the resistance change can trigger anything you want. But this works better with a clear, or semiclear liquid (and a low ambient light)

Again, it's not easy to use a vertical approach to a IR beam. It bounces off the water and return to the receiver with very little drop in intensity. You need to measure the time and not the intensity to use that setting. A foamy, turbulent surface would invalidade any of those uses. Besides, you'd need to have a sensibility of (let's say) 0.1 inches in variations to get a decent measure.

Here's a couple of more ideias :

http://clientes.netvisao.pt/carlo001/procooling/08.jpg

Capacitance measurement. The rods are isolated so there is not actual contact with the water. The system measures the alteration of the dielectric coeficient of the water as level changes and produces an alteration to the capacitance. Connected to a Wheastone capacitance bridge , it can produce (with a filter) a direct relationship between level and signal amplitude.

http://clientes.netvisao.pt/carlo001/procooling/09.jpg

Pressure switches, similar to a relay. Something like this : http://www.grainger.com/Grainger/pro...mId=1611760105

http://clientes.netvisao.pt/carlo001/procooling/11.jpg

DC-DC LVDT movement measure. Operates by amplitude changes by the movement of the coil through the lenght of the coils. Can be used in my early description.

05-02-2003, 02:09 PM	#34
TerraMex Cooling Savant Join Date: Nov 2002 Location: Portugal, Europe Posts: 870	>Also, I can probably reduce the intensity of the beam enough >that it won't penetrate water that is mixed with some sort of >semi-opaque substance. @Jsimmons You dont need that many emitters/receivers. 4 or 5 will do. But you need to plant them in the opposite wall, at the same level. When the level drops, the IR beam gets across, and triggers the receiver. That with a opaq liquid. http://clientes.netvisao.pt/carlo001/procooling/13.jpg , like this. You can use different approaches to the same type of measure with light. You can use a powerfull light on top of the res and use an LDR cell on the bottom of the res. As the level drops, more light gets to the bottom and the resistance change can trigger anything you want. But this works better with a clear, or semiclear liquid (and a low ambient light) Again, it's not easy to use a vertical approach to a IR beam. It bounces off the water and return to the receiver with very little drop in intensity. You need to measure the time and not the intensity to use that setting. A foamy, turbulent surface would invalidade any of those uses. Besides, you'd need to have a sensibility of (let's say) 0.1 inches in variations to get a decent measure. Here's a couple of more ideias : http://clientes.netvisao.pt/carlo001/procooling/08.jpg Capacitance measurement. The rods are isolated so there is not actual contact with the water. The system measures the alteration of the dielectric coeficient of the water as level changes and produces an alteration to the capacitance. Connected to a Wheastone capacitance bridge , it can produce (with a filter) a direct relationship between level and signal amplitude. http://clientes.netvisao.pt/carlo001/procooling/09.jpg Pressure switches, similar to a relay. Something like this : http://www.grainger.com/Grainger/pro...mId=1611760105 http://clientes.netvisao.pt/carlo001/procooling/11.jpg DC-DC LVDT movement measure. Operates by amplitude changes by the movement of the coil through the lenght of the coils. Can be used in my early description. __________________ "we need more cowbell."