Design Center » TriacOut12 Schematic Notes

These are notes describing the TriacOut12 triac output circuit schematic. This discusses the specific design issues of the TriacOut12 board, which is very much like the TriacOut4. This extends the general notes with the TriacOut4, and doesn't repeat that information here

Read the TriacOut4 Schematic Notes first, then read this page.

This is meant to be a general discussion, but assumes some basic electrical knowledge. We assume no liability for any content here, or what you do with it; experiment at your own risk, and with low voltages. Please let me know if you have any corrections or suggestions.

Optoisolator

The TriacOut12 uses the same design as the TriacOut4. The gate resistor has an updated value of 180 ohms for 120/240 VAC operation, and the opto is the MOC3041M with 15 mA input current.

From all the TriacOut8 options that were not carried here to the TriacOut12:
We could do a low-voltage option with 33 ohm gate resistor if needed.
We could also do a low-current option with a MOC3043M and 470 ohm pull-up resistors if needed.

DC Logic input

The Triac Output board's logic input is made up of two connectors and a pull-up resistor. These connect to the opto's LED input.

The two connectors are a right-angle square-pin header (J1), and a screw terminal block (J2). They are just in parallel with each other, to be flexible with how to connect to the board. The header allows for board-to-board connections or cables or other plugs, and the screw terminal block allows you to connect individual wires directly.

Pin 1 of the connectors is the DC supply to the pull-up resistors, typically 5 V.

Pin 2 of the connectors is not connected to anything, but is available as a DC ground for other boards, or if needed for some modification.

Pin 3 is the control for channel 1, Pin 4 for channel 2, etc. These pin assignments provide consistency for the various Triac Output boards, as the number of output channels varies.

Connect the input pins to a controller's output pins, typically a transistor driver such as a UDN2803. Pull the input to ground to turn on the AC output. The device pulling the input down must be able to sink 15 mA.

AC input and Fuse

The fuse on the TriacOut12 board is sized at 10 A, to help with the total amount of current through the board. This was a practical limit for available fuses. This fuse is rated for 125 V, so it will not work for 220 V systems. Those systems would need a fuse such as the 6.3 A 250 V from the TriacOut4 board. At your own risk, if you are going to run more current through the board, you could replace the fuse with a higher value.

Reference Designators

Just for completeness in these notes, here are some comments about the reference designator assignments (J1, R1, etc)

My goal was to assign the ref des numbers so they would be consistent from board to board, as the number of channels varied. This makes it easier to write common descriptions and instructions for all the boards. Also, I wanted to keep the general standard of having the numbers increase across the board, to locate them easily (even though these are small boards).

This lasted as long as one board – the TriacOut4 and TriacOut12 have the original numbers, but the TriacOut8 added resistors for the sink/source option. However, the pattern is similar between the boards.

The components common to all the Triac Output boards:
- Logic input connectors J1 and J2
- AC input connector J3
- Fuse F1

The components for each channel:
- Pull-up resistor R1 (R3, R5, R7, etc.)
- Opto U1 (U2, U3, U4, etc.)
- Opto output resistor R2 (R4, R6, R8, etc.)
- Triac T1 (T2, T3, T4, etc.)
- MOV1 (MOV2, MOV3, MOV4, etc.)
- Output connector J4 (J5, etc.)