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What can I substitute in place of the MCP602 in the following circuit? It is a pulse rate detector.MCP601/2/3/4 are not available where I live. I have attached the relevant instructable and the MCP602 datasheet.

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Project Instructable

MCP601/2/3/4 Datasheet

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  • \$\begingroup\$ The MCP602 is available world-wide from lots of suppliers. Try Findchips: findchips.com \$\endgroup\$ – Leon Heller Dec 6 '14 at 17:56
  • \$\begingroup\$ @Leon Heller It's not available in my country and shipping is very expensive and time-consuming.A lot of companies don't ship here anyway. \$\endgroup\$ – Undertherainbow Dec 6 '14 at 17:59
  • \$\begingroup\$ Do you understand which characteristics of the MCP602 are important? \$\endgroup\$ – Ignacio Vazquez-Abrams Dec 6 '14 at 18:11
  • \$\begingroup\$ @IgnacioVazquez-Abrams No, it doesn't go into much detail in the instructable. \$\endgroup\$ – Undertherainbow Dec 6 '14 at 18:29
  • \$\begingroup\$ Who do you prefer TI, ADI, LTI, Fairchild? BTW why don't you tell us where you come from or put this info in your profile? \$\endgroup\$ – Andy aka Dec 6 '14 at 19:30
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The important characteristics required are:-

  1. Must work on single +5V supply.

  2. Input common mode voltage range must include ground.

  3. Bias current low enough to not cause unacceptably large offset with 68k resistor.

  4. Output voltage swing of <=1.0V to >=4.0V (PIC16F628A RA4/TOCKI input levels).

The ubiquitous LM358 meets all these requirements except 4, as unfortunately it can only drive up to about 1.5V below Vcc. Output voltage could be raised by removing the LED and adding a 4.7k resistor to +5V.

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You will have to find what's available where you live. The good news is that the requirements are not very strict. All that is really needed is a dual OpAmp that operates from \$V_s\$ of 2.7V to 5.5V, with a rail-to-rail input and output (RRIO). Distributors have searchable databases. So, go to the website of a distributor that sources your location and search for part that match the criteria.

Here is an example search at Newark (Farnell), because they distribute just about everywhere.

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Well there are dual op-amps that are far superior to MCP602. For example, MAX4477, MAX4489. TLC272 has similar to MCP602 parameters and lower noise. If you're Signetics fan, then you can select their TS952 dual op-amp. All of the above are rail-to-rail op-amps and can work at 5V. If you don't need rail-to-rail, LF353 is dual version of LF351. They also have high input impedance (JFET input stage) but require higher Vcc. If you can't find a dual op-amp IC, you can just use 2 ICs like MAX4475/4478,

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AD822 can be a alternative. To find match for any ic http://radio-hobby.org/modules/analog/MPC602. Note in this website mcp602 is named as mpc602 I dont know why it may be a mistake.

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  • \$\begingroup\$ Please increase the use of your answer by adding some explanations. Otherwise you won't get any credit and it even might be flagged for deletion. \$\endgroup\$ – Ariser Feb 8 '17 at 12:40

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