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Copyright © 2004-2006
QuickSource, Inc.
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Design Center » TriacOut8 Schematic Notes
These are notes describing the TriacOut8 triac output circuit schematic.
This discusses the specific design issues of the TriacOut8 board, including the source/sink inputs, low voltage operation,
and connector options. 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.
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Here are links for various versions/sizes of the schematic. Please keep the company and copyright information intact.
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For your convenience, I've collected the TriacOut8 selection chart, schematic, board, assembly, and bill of material into a PDF file.
This should be everything you need to work with our assembled boards, do it yourself with our bare boards,
or even do the whole thing from scratch! I hope you like this enough to buy the boards
(the triac output bare boards are fun!),
but even if you don't buy from us, you may know someone who will.
These two packages are the same except for the Bill of Material spreadsheet page for the particular board suffix noted.
All the parts are listed in each spreadsheet, but may be noted as 'unpopulated' depending on the board.
However, if you would like the exact spreadsheet for a specific board, just let me know.
View/Download TriacOut8 Documentation Package PDF for -01 and -05 boards.
View/Download TriacOut8 Documentation Package PDF for -09 and -13 boards.
(If you like us, please link to our site, but please link to these design pages or the home page, and not to the PDFs and gifs directly.)
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TriacOut8 Options
The TriacOut8 series of boards has additional connector and input drive options compared to the TriacOut4 and 12,
to provide a more flexible interface to control systems.
See the TriacOut8 selection chart.
At the risk of being less "simple," the TriacOut8 accomodates different controls
and wiring:
The input logic can sink to ground in the usual manner, such as
with a 2803 transistor driver; or driven from a high side source, as with
the Olsen 595 board discussed on ComputerChristmas.com.
The control wiring can
be directly connected to a header connector, individually wired to terminal
blocks, or connected over network cable with to an optional RJ45 connector.
Finally, to be particular, although the standard 120-240 VAC circuit typically
works well down at 24 VAC, the TriacOut8 has an option to change the optos and
gate resistor to specifically operate at the lower voltages.
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Optoisolator
There is a series gate resistor between the AC line input,
and the pin 6 high side of the opto output, R3 as one example in the TriacOut8 schematic.
This resistor limits the peak current through the optoisolator.
Its value is a balance between limiting peak current, and allowing enough gate current to turn on the triac.
The TriacOut8 gate resistor has a value of 180 ohms for 120/240 VAC operation,
and a value of 33 ohms for low voltage operation such as 24 VAC.
See the Triac Series Gate Resistor
application note for details.
The TriacOut8 changed the opto to the MOC3043M opto, with a low 5 mA input current.
This allows driving with less current, which allows some logic chips such as HC to drive the board
directly without a transistor driver. This affects the selection of the pull-up resistors to pull less current.
The boards with 120-240 VAC operation (the -01 to -08 boards) use the MOC3043M opto.
The boards with 24 VAC operation (the -09 to -16 boards) use either the MOC3033M or a MOC3043M opto,
depending on availability. The MOC3043M works for all the voltages, but is more difficult to locate than the MOC3033M.
These low-current optos increased the cost quite a bit. If the low current isn't needed,
you could use a MOC3041M as on the TriacOut4, with different pull-up resistors (see input details below).
The TriacOut8 has enough options as it is, so this isn't in the catalog as a standard board.
However, we could do a standard-current option if needed.
24 VAC Operation
This is mentioned in the details above, and summarized here.
The only differences for 24 VAC instead of 120/240 VAC are:
- Gate resistor 33 ohms.
- Opto MOC3033M or MOC3043M.
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DC Logic input
The TriacOut8 logic input is made up of three
connectors and two pull-up resistors. These connect to the opto's LED input.
The two standard 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, when using the sinking configuration (see sink/source below).
This is unused in the sourcing configuration.
Pin 2 of the connectors is the common DC ground return from the pull-up resistors,
when using the sourcing configuration (see sink/source below).
This is unused in the sinking configuration.
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.
RJ45 Connector
The TriacOut8 has an RJ45 connector option for the logic inputs,
in addition to the standard right-angle and terminal block connectors.
The 8-pin RJ45 can connect to Cat5 network cable for the control wiring.
There is a jumper for the use of pin 1 of the connector.
Since the RJ45 has only 8 pins, the choice for pin 1 is to provide the power or ground,
and only control channels 2-8;
or to control all 8 channels, but require power or ground on a separate connector.
The jumper is a set of three pairs of pads on the board.
Connect one jumper pair depending on the choice for the RJ45 Pin 1.
When ordering assembled boards with the RJ45, include a comment for the RJ45 Pin 1 jumper choice.
Connect one jumper pair as one of the following:
+5V +5V supply for the sinking input configuration. Control channels 2-8.
GndGround return connection for the sourcing input configuration. Control channels 2-8.
In1Logic input 1. This controls all 8 channels from the RJ45 connector, but requires power or ground elsewhere.
Note: The connector will work with any 8-wire network cable with an RJ45 connector.
Since the inputs are low speed controls (compared to computer networks),
the phrase "Cat5" is just a common term for the cable. Any Cat speed rating will work fine.
Sink/Source Option
The TriacOut8 board introduced an assembly option to sink or source the optos.
This provides flexibility for controller boards that either sink the opto current on each input, or source the current.
When sinking, the low side of each opto is connected to each input line.
The high side of the opto has a resistor connected to a common 5 V supply voltage.
Typically a transistor driver such as a ULN2803 drives each input, sinking the current and turning on the opto.
When sourcing, the high side of each opto is connected to each input line,
and the low side has a common connection to ground.
Logic or a transistor driver such as a UDN2981 drives each input, sourcing the current and turning on the opto.
The TriacOut8 board has an option at assembly to sink or source,
by adjusting the location of the opto resistors.
The TriacOut4 and TriacOut12 boards were designed for sinking, so they expect a common 5 V supply, and each channel to sink the opto.
In the schematic, the standard sinking configuration is shown,
with the resistors and solid lines. The alternative sourcing configuration is shown with dotted lines.
To make the option simple, and avoid additional jumpers,
each opto has two series resistors on its input, one above and one below.
Each resistor is half the value of the typical single resistor, producing the same current.
Since the optos are driven by current, the total current is the same.
For sinking, the two resistors are installed in one set of pads;
for sourcing, the resistors are installed in a different set of pads.
This effectively "rewires" the optos for sinking or sourcing.
The option is laid out with 3 pads, to install the resistor on
the left or right (this is changed from the original rev A boards). For
sinking, install the resistor on the left, in the left and middle pads. For
sourcing, install the resistor on the right, in the middle and right pads.
Input current/voltage details
Specified 5 V min supply to the optos, for convenience.
The TriacOut8 uses a MOC3043M opto, with a 5 mA input.
This allows driving with less current, which allows some logic chips such as HC to drive the board
directly without a transistor driver.
Rounding up the 5 mA to the opto's recommended 8 mA,
to have some room in the design (and later notice it also gets the resistors to standard values).
The minimum needed is still just 5 mA, so logic should get away with turning on the opto.
Used a total of 440 ohms on the input as two 220 ohm resistors in series,
from a nominal 5V/8mA, calculated as follows:
Forward voltage on the opto's LED is 1.3V, so (5 – 1.3) / 8 mA
= 462 ohm. The TriacOut8 board splits this input resistance into two resistors in series (see sink/source), for 231 ohms each. Rounded the current up, and the resistors down, to a standard 220 ohm.
See these excellent posts for the values from the Computer Christmas forums, by
Dan Baldwin and
Ted Dodson.
For the max voltage, the 1/4W resistor is the limiting factor.
The two resistors actually help this.
V^2 / 220 ohm = 0.25 W, so V = 7.4 V max across each resistor, plus the opto's 1.3 V, totals 16.1 V.
If the 5 V supply is insufficient due to wire distance, it can be increased.
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AC input and Fuse
The fuse on the TriacOut8 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.
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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 resistors R1 & R2 (R4 & R5, R7 & R8, R10 & R11, etc.)
- Opto U1 (U2, U3, U4, etc.)
- Opto output resistor R3 (R6, R9, R12, etc.)
- Triac T1 (T2, T3, T4, etc.)
- Output connector J4 (J5, etc.)
Special to the TriacOut8:
- RJ45 connector
- Jumper block for RJ45 pin 1 (JP1)
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Author: Bob Cooley
Copyright © 2006
QuickSource, Inc.
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