The voltage regulators on both the BASIC Stamp 2 and Board of Education Rev C have reverse voltage protection circuits built-in. If you put all the batteries in the Boe-Bot's battery pack backwards, it won't hurt the BASIC Stamp or the Board of Education. I tested it just now to make sure. When I slid the power switch from 0 to 1, the green Pwr light on the Board of Education did not light up. If you put all the batteries in the right direction, the green Pwr light will light up as soon as you move the Pwr switch from 0 to 1 or 2. I also moved the switch to 2 with the servos connected and the jumper between the servo ports set to Vin. I waited for a while, but nothing bad happened.
I wasn't worried about the BASIC Stamp or the Board of Education, but I was a little worried about the servos. While it did no apparent damage to the servos, you can help ensure that the servos will be unharmed by leaving the jumper between the servo ports set to Vdd. That's the way we ship it in the Boe-Bot full kit. When it's set to Vdd, it puts the servos behind the reverse voltage protection built into the large, 3-pin voltage regulator on the Board of Education. It's the part labeled LM2940. The tradeoff of having the jumper set to Vdd is that the Boe-Bot will drain the batteries more quickly. When you get to page 61 in Robotics with the Boe-Bot v2.2, it shows how to change the jumper from Vdd to Vin to help make your batteries last longer. I would recommend leaving the jumper on Vin, and being careful to put the batteries in the right way from that point onward.
The other mistakes that can happen are that one, two, or three batteries get put in backwards. If only one battery is in backwards, the green Pwr light will appear to be a little dimmer than usual. When you try to download a program to the BASIC Stamp, the BASIC Stamp Editor software will tell you "No BASIC Stamp Found" because there's not enough supply voltage to make the BASIC Stamp wake up. If you put two batteries in the right way, and two batteries in the wrong way, they will cancel each other out, and the BASIC Stamp's supply will be very close to 0 V. The green light won't come on, and the BASIC Stamp won't work. If you put 3 batteries in backwards, you are applying -3 V, which will result in the same symptoms as all batteries in backwards (-6 V). The green light won't come on, and programs will not download to the BASIC Stamp until the batteries are put in the right direction.
In general, always move the 3-position switch to position 0 before loading or unloading batteries or adjusting circuits that you have built on the Board of Education. If you move the 3-position switch to either 1 or 2 and the green Pwr LED light is dim or does not turn on, move the 3-position switch back to 0 immediately and look for a battery or circuit mistake.
On page 17 or Robotics with the Boe-Bot, it shows a picture of the inside of the battery pack where there are pictures of little batteries in each slot that show which end the bump (+ terminal) connects to and which end the flat (- terminal) connects to. Please do direct their attention to this in your video.
Comments
The voltage regulators on both the BASIC Stamp 2 and Board of Education Rev C have reverse voltage protection circuits built-in. If you put all the batteries in the Boe-Bot's battery pack backwards, it won't hurt the BASIC Stamp or the Board of Education. I tested it just now to make sure. When I slid the power switch from 0 to 1, the green Pwr light on the Board of Education did not light up. If you put all the batteries in the right direction, the green Pwr light will light up as soon as you move the Pwr switch from 0 to 1 or 2. I also moved the switch to 2 with the servos connected and the jumper between the servo ports set to Vin. I waited for a while, but nothing bad happened.
I wasn't worried about the BASIC Stamp or the Board of Education, but I was a little worried about the servos. While it did no apparent damage to the servos, you can help ensure that the servos will be unharmed by leaving the jumper between the servo ports set to Vdd. That's the way we ship it in the Boe-Bot full kit. When it's set to Vdd, it puts the servos behind the reverse voltage protection built into the large, 3-pin voltage regulator on the Board of Education. It's the part labeled LM2940. The tradeoff of having the jumper set to Vdd is that the Boe-Bot will drain the batteries more quickly. When you get to page 61 in Robotics with the Boe-Bot v2.2, it shows how to change the jumper from Vdd to Vin to help make your batteries last longer. I would recommend leaving the jumper on Vin, and being careful to put the batteries in the right way from that point onward.
The other mistakes that can happen are that one, two, or three batteries get put in backwards. If only one battery is in backwards, the green Pwr light will appear to be a little dimmer than usual. When you try to download a program to the BASIC Stamp, the BASIC Stamp Editor software will tell you "No BASIC Stamp Found" because there's not enough supply voltage to make the BASIC Stamp wake up. If you put two batteries in the right way, and two batteries in the wrong way, they will cancel each other out, and the BASIC Stamp's supply will be very close to 0 V. The green light won't come on, and the BASIC Stamp won't work. If you put 3 batteries in backwards, you are applying -3 V, which will result in the same symptoms as all batteries in backwards (-6 V). The green light won't come on, and programs will not download to the BASIC Stamp until the batteries are put in the right direction.
In general, always move the 3-position switch to position 0 before loading or unloading batteries or adjusting circuits that you have built on the Board of Education. If you move the 3-position switch to either 1 or 2 and the green Pwr LED light is dim or does not turn on, move the 3-position switch back to 0 immediately and look for a battery or circuit mistake.
On page 17 or Robotics with the Boe-Bot, it shows a picture of the inside of the battery pack where there are pictures of little batteries in each slot that show which end the bump (+ terminal) connects to and which end the flat (- terminal) connects to. Please do direct their attention to this in your video.
Andy