Other Parts Discussed in Thread: LMC662, LMC6081, TLV9002, TLV9062, OPA2170, OPA2172, TLV2170, TLV2172
hi Everyone
I am new to electronics
I wanna to use a sensor having mV output which is not suitable for arduino
i have found that this can be done with non inverting operational amplifiers
Can you please guide me how can i do this
what components should i use
Sensor MG812
Load 100mA
Thanks in advance
Hi Harjot,
usually, the LMC662 is used for this purpose because of it's extremely low input bias current and low cost. This circuit could be used:
Because the zero emf of sensor is up to 500mV, only a gain of 7.8 is used. R3 protects the input. Feedback resistances R1 and R2 are kept low to keep the OPAmp stable. C1 provides a phase lead compensation to further stabilize the OPAmp.
Take care: This circuit is still producing rather high noise and has problems driving capacitive loads. This has to do with the LMC662 which does not like capacitive loads. So, it would be wise to add a passive low pass filter and a buffer. What do you want to drive with this circuit? An ADC input? Or a cable?
Kai
Hi Hojart,
if you have an Arduino with ATMEGA328 and want to directly drive the ADC input, you could use the following circuit:
Corner frequency of low pass filtering is about 150Hz. If you need an OPAmp with lower input offset voltage, take the LMC6081.
Kai
Hello,
Here's a link to a good design guide for non-inverting amplifier circuits. The LMC662 is a good amp but there are much newer alternatives which perform better for lower costs.
For +1.8V - 5.5V supplies look at the TLV9002 (1MHz) or TLV9062 (10MHz).
For +4.5V - 36V supplies look at the TLV2170 (1MHz) or TLV2172 (10MHz). The OPA2170 and OPA2172 are higher performance versions of the TLV devices.
