I have 'recovered' a C4570HA amplifier chip (from a defunct a music amp) and am hoping to put it to use.

enter image description here

I have a sensor (i'm building a pyranometer with a PV cell) that produces 0-40mV DC. I want to bump that up so I can read on an Arduino. Amongst other things I'm going to connect pin #3 to GND and pin #4 to sensor pos, then measure pin #2 (Vout) on one of analog pins of arduino.

What I am trying to understand is (pls bear in mind I have no idea what I am doing)

  1. Can i use C4570 for this or am I wasting my time and,
  2. What gain can I expect? gain vs frequency chart from datasheet below. I can appreciate the frequency of the audio context where I got the chip, but what is the 'frequency' of my input? Am I down near zero (good) or up towards infinite? enter image description here
  • 3
    \$\begingroup\$ I have no idea what I am doing Hmm, then why not get that idea first and then come back when you have a proper question. connect pin #3 to GND and pin #4 to sensor pos No one here is going to check if that makes sense. You need to draw a schematic and then maybe you will get an answer. You're using an Arduino, which runs on 5 V. This C4570HA opamp will not work at 5 V, it needs 8 V or more. A suitable opamp like the LM358 costs almost nothing so yes, this opamp is pretty useless for what you're doing/trying to do. \$\endgroup\$ Dec 22 '16 at 6:58
  • \$\begingroup\$ @FakeMoustache Thanks. You could probably have just written last two sentences, toning down the last one. Bad karma. Wanted to use the C4750HA for the joy of using it. \$\endgroup\$
    – Jon
    Jan 13 '17 at 6:23

You might be able to use that old recycled chip, but since you don't know if it even works, it is puzzling why you would want to waste your time with it instead of spending a few pennies (literally) to get a new, proper op-amp. In addition. You can use an op amp which you can power from the 5V that operates the Arduino. If you use that antique C4570HA, it wants ±15V and where you plan to get that power?

Your circuit makes no sense at all. Study op-amp circuits to see how an op-amp is used in a proper amplifier circuit with gain. For example: http://www.electronics-tutorials.ws/opamp/opamp_3.html

What voltage range do you want to send to the Arduino? For example, if you want a 0~4V signal, then you will need to amplify your 40mV signal x100 = 40dB gain.

If your signal is DC that means 0 Hz.

  • \$\begingroup\$ Thanks. New to electronics so was in dark where to start. 'op-amp' was the search term I was after, never even heard of them. Perfect. I persevered with the C4570HA, mostly through spite and nostalgia (I got it out of an amp that I saved up for for months as a teenagaer). I failed to get it to do what I wanted but learnt a great deal. Ho hum. \$\endgroup\$
    – Jon
    Jan 13 '17 at 6:32

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