Switchable constant current circuit (7 -> 14ma) against changing load (20 -> 2100 Ohms)
Budget: £20 – £250 GBP
I have got a long way through this project myself, however, I now have a circuit that simulates correctly but fails when created in hardware. I have tried to work out what is wrong as in the simulation all components are within spec, however in reality this is obviously not the case.
I'm looking for an experienced electrical engineer to help me to develop a switchable constant current circuit so I can output a 7-14mA signal from a 10-15V source against a changing load resistance. I want both simulation and physical demonstration of the solution.
I am trying to replicate an ABS sensor signal, for which I believe, and example circuit is below. I need to replace the Schmitt trigger section with a 3.3v microcontroller output and have a square wave output with a transition time of no more than 4us.
The standard operation will be switching against the 20 Ohm resistance, however during diagnostics – this is switched to an 1870-2100 Ohm resistor leading the voltage to increase for 7mA from 0.14v -> ~12v.
I will share my current progress with a schematic, LTSpice model and PCB design files once I have seen someone can help me with this task – ideally someone who can show they have done something similar before.
I look forward to finally finishing this project with someone!
I'm looking for an experienced electrical engineer to help me to develop a switchable constant current circuit so I can output a 7-14mA signal from a 10-15V source against a changing load resistance. I want both simulation and physical demonstration of the solution.
I am trying to replicate an ABS sensor signal, for which I believe, and example circuit is below. I need to replace the Schmitt trigger section with a 3.3v microcontroller output and have a square wave output with a transition time of no more than 4us.
The standard operation will be switching against the 20 Ohm resistance, however during diagnostics – this is switched to an 1870-2100 Ohm resistor leading the voltage to increase for 7mA from 0.14v -> ~12v.
I will share my current progress with a schematic, LTSpice model and PCB design files once I have seen someone can help me with this task – ideally someone who can show they have done something similar before.
I look forward to finally finishing this project with someone!