# is there a Counter to control DC voltage up and down.

#### hp1729

Joined Nov 23, 2015
2,304
Hey guys
Sorry it was very late last night (my time) when I posted.
Here is some more details.

1. The unit must be very small for robotics it is on a DC system, power supply 11.5 thru with a step down chip to 5v to operate the flow valve signal.
2.There is no pump the liquid in the resivour is pressureized by air from .01 to 8 psi depending how far a valve is opened
3. it must be able to measure .3oz per minute up to 8oz per minute
4. the liquids are flammable, 1 is petroleum based, the other is alcohol based
5. there can only be 1 flow meter, due to space restrictions.
6. The flow meter in the post has a pulse signal of 10000 pulses per liter, it uses hall effect sensors to create the pulses
7 It must be able to measure from 0 oz to between 2 and 32 oz and everything in between depending on the size of the resivour.
8. it needs to be adjustable I.e. if a 2oz tank is used 100% voltage out put would be shown when full and 0 voltage output when tank is empty, if a larger tank is used it must be easily adjustable to show 0%(5v)empty and 100% (11.1v) full.
9. if a tank is partially filled say 90% it must show 90% voltage on the voltometer, and it must be able to count down backwards from that 90% till it hits 0%
10. the out put voltage to the voltometer can a continuous drop or be stepped between 8 and 16 times, (the voltage is dropped 16 times by .4v increments starting at 11.7v-11.3 -10.9-10.5......
For continuous; lets say you have a 2oz resivour the minimum the flow sensor can read is .3oz per minute. at minimum flow it would take 6 minutes to flow out. at maximum flow it would take 5 seconds. That said the sensor does 1 rotation pulse for every .00338oz (10,000 rotations per litre, 1 litre = 33.8oz / 10,000 = .0038oz/pulse) passed thru. The unit is sensitive for 100 rotations or .33oz So if you have 2 oz that means that a full tank will have 526 rotations/pulses. Now the voltage out to the voltometer can be dropped from 11.7v 100% output down to 5v output 0% with over 526 pulses which would be .0126v per rotation. Or It can be stepped down by 16 times 526/16= per 33 pulses the voltage is dropped down by .418v

Because the volume can change issue is it has to be adjustable, lets say I choose to use a 48oz tank. this would mean that it would have a total of 48oz / .00338oz/pulse = 12631 pulses for a 48oz tank 11.7v-5v= 6.7v /12631 pulses = .00053044097v/pulse OR the out put voltage could be dropped 16 times = 713 pulses voltage is dropped by .418
11. Thus It the unit must be able to count the number of pulses going into the resivor and then subtract that controlling the output voltage going to the voltometer automaticly.
12. There could be a switch to flip from the counters + count to the negative count
Nope. That leaves me out.

#### born2dive00

Joined Oct 24, 2016
285
Answering the questions posted.
Here is the pdf of the flow meter http://www.btflowmeter.com/fileadmin/PDF/92202851_FCH-m-PP-LC.pdf
Below is a outline of what I am trying to do

I was thinking of using a flip flop to store the number if pulses on the positive counter, then flipping a switch allowing it close to the negative count opening the positive count. I think this would work.

How do I get the system to recognize different volumes of liquids but still having the same 16 step voltage drop all the time?

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