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Capacitive touch switch for large (larger than human) metal objects

Hi All,

I'm trying to make a capacitive touch switch that I can integrate into large metal objects and turn them into sensors.  Think of there being a 400lb engine on a pedistol (assume the entire object body is conductive), I want to have it where when a person touches the engine a video is triggered elsewhere in the room.

Heavy Duty Mechanical Components

Hey Guys,

I'm looking to make a semi-functional heavy duty robotic arm.  It's for an art project so it won't need absolute precision, it's more for aesthetics and entertainment.  The arm could potentially be 4-5 feet but it wouldn't need to lift anything except itself or a flashlight.

I have a handle on programming, metal fabrication, and electronics.  

Stepper motor holds at full current and makes noise, smooth otherwise

Hello,

I have the following:

EasyDriver stepper motor driver

Bi-Polar stepper motor 6 wire

I am using Red/White and Yellow/Black, which means I'm using half coil.  My understanding is this allows me to use the full current (and presumably have more holding strength).

UART level translation, what type of translation IC is required?

I have two devices, and need to figure out how to translate between them for 2 wire UART.

U-Blox NEO-5G, 1.8V
Input low:  0.22V (MAX)
Input high: 0.91V (MIN)
Output low:  0.4V (MAX)
Output high: 1.4V (MIN)

Telit GC864
Input low:  0 - 0.5V
Input high: 2.1 - 3.3V
Output low:   0 - 0.35V
Output high: 2.2 - 3.0V

UBlox -> Telit
LOW: .4V (MAX) -> 0-0.5V   (WORKS)
HIGH: 1.4V (MIN) -> 2.1-3.3V (DOES NOT WORK)

Does UART require a pullup resistor?

I am trying to understand how UART communication works.

I have not read anything stating that pullup resistors are required for UART, but conceptually some type of pullup is in fact required because otherwise there would be an unknown state.

Is it part of the UART standard that each device on the bus must have it's own pull-up resistor?  If so how can this be because if the pull-ups are of different voltage then the state is again unknown.

Thanks

Analog Logic Circuit with Timer/Delay, need some help

Hello

I have a processor which needs to be powered on by pulling a pin LOW for 1 second.  I would like to set the system up so that whenever a battery is present, the processor turns on.  I have a programming background so I am having a little trouble turning ths into an analog design.

 

Here is what I have:

3.7V battery input (Li-ion), 900 - 1100mA, call it BAT

ON# pin, which needs to be pulled LOW for 1 second.

POWRMON pin, which is HIGH when the unit has been turned on OR ON# pin is pulled LOW.