newbie question about max current, project cases, & pin connectors

nthomas819

Hello everyone,
I'm new to this, but I've found that whole parallax system allows for quick learning and satisfying results.· I have a few questions that I know will be pretty basic to this group.
1)· The current limit for an I/O pin is 20mA.· Does this apply to the Vss or Vdd pins as well?· Those pins are still routed through the chip, so I'm sure there is some limit.· But if everything I can hook up to is limited to 20 mA, then how do I use the BS2 and a transistor to control a higher current?
2)··I've been using the·BS2 Carrier board to finalize projects.· The BS2 chip mount has rows of pins sticking up on each side of it.· Is there a standard female connector to plug into this?· It would be useful to connect to the BS2 via a plug sometimes rather than soldering.
3)· Also concerning the carrier board...is there a consensus on the best project case that fits it (with the battery) the best.· I couldn't find any for sale by parallax.· It seems odd since they have just about everything else to do a project, and naturally, you need a box to mount it in to finish it.

Thanks in advance,
Neil

Lab Rat

1) with an external power source
2) never solder to the stamp. insteadpurchase multiple ic sockets it saves the stamp
2 out of three is a good average

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I`m not prejudice I hate everyone equally

allanlane5

A transistor is a current switch. So, it allows a little bit of current between the base and emitter to control a larger current between the collector and emitter. Thus a BS2 can with a mA or two through the base-emitter path control 50 mA between the Collector-Emitter path. That assumes a transistor with a Beta of 50.

If you need to control more current than that, there's a Darlington Array. And if you need more than that, there's Power Transistors designed for switching 1 to 5 amps.

There's a wonderful Nuts and Volts article on "The BS2 on Steroids" that's pretty thorough in how to interface the BS2 to provide switching for largish currents.

Mike Green

1) I believe the Vss and Vdd currents are limited to 100mA. The Stamp uses a PIC16C57 as its processor. You can download the datasheet from Microchip and look at that for the details.
2) There are a variety of manufacturers making standard 0.1" female headers in all kinds of widths. Usually I buy the plastic shells and metal inserts separately to make up my own cables, but you can buy ready-made cables. The inserts are designed for crimping with a specific tool, but I use a needle nose pliers for crimping and a drop of solder to make sure there's a good connection. Look in the Jameco or Mouser or DigiKey on-line catalog.
3) Can't help you there