How to create a voltage selector circuit

Thread Starter

kmesne

Joined Mar 13, 2019
13
Hi I want to make a voltage selector circuit with opamps and diodes etc. (no IC's except opamps) but I couldn't find a way, do you have any advice for me ? Its like a dot display level meter (dot not bar) but I can not use LM3915 etc.

I have a varying DC voltage and want to make a circuit that choose a specific path for its amplitude. I don't need to save dc input I don't need its information, I only want to know its amplitude Voltage range

Like if dc source has 0-1V current flow goes path 1, if it has 1-2V current flow goes path2, if it has 2-3V current flow goes path3 etc. But when it goes from path 3, it cannot goes through path 1 and 2.

I know that I will use comparators but couldn't find a logical connection which will stop unneeded paths.

(Paths will not be open circuited as I show it on image there will be more connections to them by using buffers.)

Thanks
 

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Thread Starter

kmesne

Joined Mar 13, 2019
13
If you look at the LM3915 dtatsheet there is a block diagram showing how it works - all you have to do is to copy it.
I tried to make something I figured out this circuit. But I couldn't find a way to block lower levels. For example if I have 5 V as in figure, it doesn't go through R3 yes its achieved, but it shouldn't go through R1 as well it should only go through R2.Adsız.png
Transisors and other IC's forbidden except only for opamp.
 

ericgibbs

Joined Jan 29, 2010
9,116
hi k,
Who suggested using diodes in that way.?
A simpler circuit would be a series resistor divider chain for the voltage reference levels.
E
 

Thread Starter

kmesne

Joined Mar 13, 2019
13
hi k,
Who suggested using diodes in that way.?
A simpler circuit would be a series resistor divider chain for the voltage reference levels.
E
I came up with that idea. I am trying to block other voltage ranges. Are you talking about simple voltage divider? How can I obtain my voltage selector without opamps ? I want my current choose only one specific path according to its voltage range.
 

ericgibbs

Joined Jan 29, 2010
9,116
hi,
I follow what you are trying to do.
How can I obtain my voltage selector without opamps . I am not suggesting doing it without OPA's

Look at this image from the LM3914, uses a resistor divider for the voltage reference levels.

E
Update:
Added the Mode circuit, for single Output.
 

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Thread Starter

kmesne

Joined Mar 13, 2019
13
hi,
I follow what you are trying to do.
How can I obtain my voltage selector without opamps . I am not suggesting doing it without OPA's

Look at this image from the LM3914, uses a resistor divider for the voltage reference levels.

E
Update:
Added the Mode circuit, for single Output.
It has transistor in it I can't use transistor as well.

What is wrong with my Circuit ?
 

ericgibbs

Joined Jan 29, 2010
9,116
hi k,
Look at this option as basic starting design.
I know that its does not display a single output state, but you should be able to figure out the remainder of the circuit yourself.
As this is Homework I cannot give a final design.
E

Added the asc file.
AAA 075 09.20.gif
 

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ci139

Joined Jul 11, 2016
1,017
I know that I will use comparators but couldn't find a logical connection which will stop unneeded paths.
if you set your comparators to
trigger on
at range.low.limit
then you can mod the detection biasing so
that if the next range goes on ← then this on
cancels all the lower ranges

. . . it can be implemented by diode commutators or
with diodes and resistive dividers
 
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