March 15, 2011
about 4 years ago
Yes, it appears to be a PH series, which has 2-mm pin pitch. (I, too, was curious about the part characteristics.) Get the datasheet at JST PH Connector and the part number seems to be S2B-PH-SM4-TB for the 2-pin, side-entry, SMT-type, shrouded header.
Oh, I forgot to mention something important that I observed about using the EL Escudo with an Arduino Duemilanove and a 3-V-powered inverter. If the power supply is insufficient (say, the 3-V battery is weak), then the Arduino might reset itself when the load increases (for example, by calling the all_on method) because the increased load drops VDD below the reset-circuit threshold.
Once reset, the Arduino works normally until all_on is called again, and the cycle repeats.
Using the EL Escudo with an Arduino Duemilanove and a 3-V-powered inverter:
In my experience, this works most easily:
1. Don’t plug in the EL Escudo into the Arduino yet.
2. Connect the Arduino to USB and program it.
3. Unplug the Arduino from USB.
4. Plug in the EL Escudo to the Arduino.
5. Plug in the inverter and EL wires to the EL Escudo.
6. Supply 3.3V to the +5V and GND pins on the Arduino.
Backfeeding 3.3V into the output of the unused 5-V regulator on the Arduino should be safe, as the regulator is effectively shut down.
For subsequent program/test cycles, it is easier to unplug and plug in the EL Escudo than it is to unplug and plug in the two small connectors for the inverter.
About the 3-V-supplied inverter, SparkFun SKU COM-10201: I found that there is an internal connection between GND on the input and HVGND on the output. So a jumper on the EL Escudo board is unnecessary when using this inverter.
In the library, I found the following correction is necessary in EL_Escudo.cpp because the triac gate must be on continuously to keep the EL wire on, as a pulse would turn it on only for a half cycle of inverter AC output (and at 400Hz, would not even be visible):
for(int i = A; i < = H; i++) EL.on(i);
I found errors in the library. Assuming that GND and HVGND are tied together (on the board or through the inverter), HIGH supplies gate current to turn on the triac, and LOW turns off the triac. (I don’t let the gate lead float [by changing the pin mode to INPUT], as capacitive coupling from main terminal 2 to the gate could cause unwanted triggering.)
So here are the changes I needed to make in EL_Escudo.cpp:
void EL_EscudoClass::on(char channel)
void EL_EscudoClass::off(char channel)
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