What is this component, and did I make this schematic correctly?

Question

This control board is from a mini-split heat pump. It sits on the outside of the unit and receives signals from a remote control. It's from this discussion here.

It's a single-sided board - am I getting the schematic correct, and is this typical for an infrared sensor e.g. used with remotes?

The brown and orange aren't clearly identified. If those were accidentally swapped will they just light the wrong light? Or could something worse happen?

schematic

^{simulate this circuit – Schematic created using CircuitLab}

Bonus questions: Why two capacitors? What's the point of the resistor (is that a resistor?) in series with red/supply?

Bend the three-terminal device away from the board to get the part number on its flat face. LAMP1 and 2 should probably use the LED symbol. — Transistor, Jan 14 '23 at 07:46

score 7 · Answer 1 · edited Jan 14 '23 at 06:22

7

The two caps provide good supply bypass. The electrolytic does the low frequencies and the ceramic handles the high frequencies.

R1 is an idiot resistor. Imagine if U1 fails short circuit -- R1 keeps currents safe.

edited Jan 14 '23 at 06:22

Harper - Reinstate Monica

21,639
27
68

answered Jan 14 '23 at 04:03

Autistic

14,235
2
27
65

2

R1 could also be for noise filtering - R1 and C1/C2 form a low pass filter for the supply. – jpa Jan 14 '23 at 12:43
2

R1 might also prevent destruction of U1 if cables get mixed up and power is applied in the wrong polarity. – Michael Karcher Jan 14 '23 at 13:03

score 4 · Answer 2 · answered Jan 14 '23 at 05:09

4

Chances are the three-terminal component is an IR receiver.
Either there is a hole/window in the casing, or that would need to be somewhat transparent to IR.

answered Jan 14 '23 at 05:09

greybeard

1,469
1
4
17

What is this component, and did I make this schematic correctly?

2 Answers2