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You need to ground the negative terminal of the thermopile.

The LM358 is a single-supply op-amp and it will work with a 5V supply, however the output voltage will be limited to about 0-3V over temperature and a bit more than that typically.

The LM358 also has a typical offset voltage that can be as much as your entire signal, so it's not a great choice for this application. Ideally get a better op-amp or at least give the op-amp a negative supply and trim the offset out. The sample circuits on the datasheet show a pseudo-ground created by a Zener diode to provide some offset.

If the op-amp happens to have a large negative offset you'll get about 0V out pretty much regardless of the thermopile output, even when it's connected properly.

You should also match the impedances seen by the inputs and add some low pass filtering to an amplifier with such a high gain. For example, a 100nF capacitor across the 1M and another 100nF from the non-inverting input to ground.

You need to ground the negative terminal of the thermopile.

The LM358 is a single-supply op-amp and it will work with a 5V supply, however the output voltage will be limited to about 0-3V over temperature and a bit more than that typically.

The LM358 also has a typical offset voltage that can be as much as your entire signal, so it's not a great choice for this application. Ideally get a better op-amp or at least give the op-amp a negative supply and trim the offset out. The sample circuits on the datasheet show a pseudo-ground created by a Zener diode to provide some offset.

If the particular op-amp sample you have happens to have a large negative offset you'll get about 0V out pretty much regardless of the thermopile output, even when it's connected properly. If it's a positive offset you'll see a large output voltage (as much as 3V) even without a thermopile signal.

You should also match the impedances seen by the inputs and add some low pass filtering to an amplifier with such a high gain. For example, a 100nF capacitor across the 1M and another 100nF from the non-inverting input to ground.

A suitable amplifier would be the NCS325SN2T1G which costs a bit more than an LM358 (32 cents in 100's) but performs much better in this application (low supply current, rail-to-rail input and output, microvolt offset). Don't forget that if you need negative output you need to give it a negative supply (and that particular op-amp can only handle 5.5V so something like -1 + 4V.

You need to ground the negative terminal of the thermopile.

The LM358 is a single-supply op-amp and it will work with a 5V supply, however the output voltage will be limited to about 0-3V over temperature and a bit more than that typically.

The LM358 also has a typical offset voltage that can be as much as your entire signal, so it's not a great choice for this application. Ideally get a better op-amp or at least give the op-amp a negative supply and trim the offset out.

If the op-amp happens to have a large negative offset you'll get about 0V out pretty much regardless of the thermopile output, even when it's connected properly.

You should also match the impedances seen by the inputs and add some low pass filtering to an amplifier with such a high gain. For example, a 100nF capacitor across the 1M and another 100nF from the non-inverting input to ground.

You need to ground the negative terminal of the thermopile.

The LM358 is a single-supply op-amp and it will work with a 5V supply, however the output voltage will be limited to about 0-3V over temperature and a bit more than that typically.

The LM358 also has a typical offset voltage that can be as much as your entire signal, so it's not a great choice for this application. Ideally get a better op-amp or at least give the op-amp a negative supply and trim the offset out. The sample circuits on the datasheet show a pseudo-ground created by a Zener diode to provide some offset.

If the op-amp happens to have a large negative offset you'll get about 0V out pretty much regardless of the thermopile output, even when it's connected properly.

You should also match the impedances seen by the inputs and add some low pass filtering to an amplifier with such a high gain. For example, a 100nF capacitor across the 1M and another 100nF from the non-inverting input to ground.

You need to ground the negative terminal of the thermopile.

The LM358 is a single-supply op-amp and it will work with a 5V supply, however the output voltage will be limited to about 0-3V over temperature and a bit more than that typically.

You need to ground the negative terminal of the thermopile.

The LM358 is a single-supply op-amp and it will work with a 5V supply, however the output voltage will be limited to about 0-3V over temperature and a bit more than that typically.

The LM358 also has a typical offset voltage that can be as much as your entire signal, so it's not a great choice for this application. Ideally get a better op-amp or at least give the op-amp a negative supply and trim the offset out.

If the op-amp happens to have a large negative offset you'll get about 0V out pretty much regardless of the thermopile output, even when it's connected properly.

You should also match the impedances seen by the inputs and add some low pass filtering to an amplifier with such a high gain. For example, a 100nF capacitor across the 1M and another 100nF from the non-inverting input to ground.