I need an 8 mA current source

I need a fixed mA source ( between 8 to 12 mA ) to be connected into 24V dc circuit.
attached a circuit from (Radio Shack Engineer's Mini-Notebook - Op Amp IC Circuits ).
Is it ok to connect my circuit instead of the LED ?

Thanks

Possibly?, but as you don't give any details it's impossible to say!.

Sorry fo lake of details

Nigel Goodwin said:

Possibly?, but as you don't give any details it's impossible to say!.

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Thanks Nigel, and sorry for few details in all my threads but thats because i'm still a new member. so what information is required ?

aljamri said:

Thanks Nigel, and sorry for few details in all my threads but thats because i'm still a new member. so what information is required ?

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About what the device is you're wanting to connect in place of the LED, as long as it's a two lead passive device, with a resistance inside the acceptable range for the circuit, it will be fine.

The story

I'm working in the Maintenance of Water Blending Stations where we use DCS consists of several PLCs, each controls part of the Station.

In our process, the control signal is (4-20 mA) using series power looped supplied with 24V dc.

In one of the Motor control circuits, a Flow Transmitter which gives ( 4-20 mA ) signal is defected, and the whole group has no Auto control. It is know working on Manual Mode of operation.

My idea is to replace the Transmitter with a fixed mA source to make the whole loop active again and put the control on Auto.

Sorry if It shows that I'm talkative, but still I'm ready to give more details if it is required.

Thanks

Right, the reason I was asked was specifically if it was something like a 4-20mA circuit!. The reason is that you have to be careful about power supplies and connections - as long as they are all isolated from each other there won't be any problem, are the inputs isolated? - if so it's fine, but if not, as long as you operate this from a seperate supply it should be fine.

aljamri said:

My idea is to replace the Transmitter with a fixed mA source to make the whole loop active again and put the control on Auto.

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That's a really bad idea and could cause you to lose your job if bad things happened. Placing a control loop into auto without proper feedback signal is dangerous and can also cause serious accident, flood the place and kill people.

The proper way is to repair or replace the faulty transmitter so that the auto loop works again. If you can't because of shortage of time, money or spares, then you have no choice but to let the loop runs in manual mode.

yes indeed " SAFETY FIRST "

eblc1388 said:

That's a really bad idea and could cause you to lose your job if bad things happened. Placing a control loop into auto without proper feedback signal is dangerous and can also cause serious accident, flood the place and kill people..

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Again less information leads to wrong pictures, Thanks to eblc1388, Safety is my first concern in my job even somebody call it "sort of bureaucracy". but I do belief " SAFETY FIRST ".

What I'm going to replace is a known flow rate , that is given by a particular pump. This flow will not be changed in any case as long as the pump running (fixed speed Motor ).

eblc1388 said:

The proper way is to repair or replace the faulty transmitter so that the auto loop works again. If you can't because of shortage of time, money or spares, then you have no choice but to let the loop runs in manual mode.

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Its not simple device (for us) to repair and Manufacturer gave the will known replay for our requests : "OBSOLETE" that what made me to suggest this solution, especially if you know that a cascade of operations depend on this group.

Thanks