Boosting an Analog input signal

[RPosty]

I work on really old CNC/Laser systems and noticed that when I use my analog input of 0 to -8v that when the laser it is feeding loads the signal down quite a bit. -8v becomes about -2v. These two pieces of equipment do not normally work together, but I have every other function working perfectly. So looking for a simple idea to boost its strength. Unfortunately the controller does not spec how much current it can deliver and the laser doesn’t spec how much current it demands. Ideally I’d also like to make it adjustable so the 0 to -8v will result in 0 to -5v, but that’s not critical.

"I am stuck on Band-Aid brand, 'cause they are stuck on me"

 

[waross]

How about a PID controller.Just use the Proportional feature.
High impedance input and robust output.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[RedSnake]

A good start would be what is the brand and number of the controller and the laser?

BR A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[thebard3]

Use something like this--

https://www.acromag.com/product-cat...20ma-isolators/2-wire-loop-powered-isolators/

Brad Waybright

The more you know, the more you know you don't know.

 

[IRstuff]

I don't know if this part is still available, or what the replacement might be, but we used to us the LH0063 buffer amp from National Semiconductor to probe interior nodes inside semiconductor chips. The LH0063 put out 100 mA at digital rates and had a gain bandwidth of nearly 100 MHz

https://www.digchip.com/datasheets/parts/datasheet/321/LH0033-pdf.php

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[LionelHutz]

Like thebard3 posted, there are lots of process signal buffers or isolators out there that would do all of what you want.

 

[RPosty]

Lots of good starting points for me, I never even thought of using a pid controller. I need to dig into the schematics I guess to see what amplifier the analog input is using and also the ic the laser is using.
The controller is a 1980’s vintage Anorad Anomatic II which is no longer supported by the manufacturer. The Laser is an old Raytheon SS550 welder/driller. Also old and there is only a small handful of us that support these anymore.
I did find the circuit originally used between these, it had an old AD510JH op amp that operated on + and -15vdc. Most of the electronics in the laser operated on +-15vdc. Would like something more modern, but I think I can still get those chips, so may just build the original circuit


I’m not an electronics engineer, I am more of a repair guy.

"I am stuck on Band-Aid brand, 'cause they are stuck on me"

 

[waross]

With a PID controller, with adjustable span and zero and outputs that are configurable with either an elevated zero or a non-elevated zero. You may further adjust the output voltages with voltage dividing resistors or generate a desired output voltage by dropping a milli-Amp output across a suitable resistor.
When calculating resistance values remember that the input resistance of the load should be part of the calculations.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!