I want to replace an analog meter with LED bar.

I am building a balancer for a model turbine. The circuit diagram I have is for an 1mA meter for measuring the strength of the piezo sensors and the other is a 5mA meter for the motor rpm. I would like to replace the analog meters with LED bars instead. I do not have a lot of electronic experience, so would appreciate some help.

Balancer circuit.

Yes you can buy drop in (electrical equal not mechanical) for analog meters. The analog meter has an impedance plus it has a full scale reading and that is all you need to have (info) to replace.

So both the meters you have, a 1mA = full scale and the 5 mA = full scale are milliamp meters with built in current shunts (impedance). The digital bar graph are virtually identical in that sense, they have shunts. Now they don't have to have the exact same shunt but it would be best because it won't effect your existing circuit. That would be the cleanest way.

On the other hand you can get generic bar graphs and provide your own shunts, which you already have with your existing analog meters, you just have to bring out the two shunt wires, and the two sense wires. The generic bar graphs are generally the volt meter type in the sense they are very high impedance, you simply connect to the sense wires on the current shunt. You can then calibrate full scale your self. Calibration would be full scale = 1mA or 5mA.

So two ways:

1) Buy drop in replacements
2) Use your existing current shunts in your old meters & buy generic bar graph, hook it up, calibrate full scale.

LED bar graphs have a very low innate accuracy.
Basic digital panel meters are very cheap and provide a (relatively) very high degree of accuracy.

If you would like to post the circuit diagram, we could provide more specific support and advice.

Thanks, Sorry my electronic knowledge is very limited. What is a drop in replacement? and a generic bar graph? Where do I get hold of them?

You could use an Lm3914 with additional circuitry but for your current through the motor you would need to add a current sensing device such as an op amp but as Frank says they are not highly accurate Youd be better off using a micro with A to D conversion to achive what you want with digital readout