Some cool parts for microcontroller projects

The SN74HC595 shift register

The SN74HC595 is an 8 bit parallel out, serial in register in a 16 pin DIP package. It can be used to expand a couple of pin to 8 outputs.

The TMP36 temperature sensor

The TMP36 temperature sensor is an Analog Devices part. It is a 3 pin device in a TO-92 package like a small transistor. It yields a 750 millivolt output at 25 degrees C and has a linear voltage change of 10 millivolts per degree C. Accuracy is a couple of degrees. It is compatible with the LM50 from National.

The 1a57hr opto-interrupter module

The gp1a57HR is an opto-interrupter module from Sharp. Mine are marked with "1A57HR". It has a huge 10mm gap (I would prefer something smaller, but we can make this work). The emitter is a diode that can take up to 50 mA, the sensor is a photodiode and enough circuitry to give a nice TTL level output.

Playing with one of these, I find that the emitting diode drops 1.12 volts and I can drive it nicely from 5 volts with a 1K resistor (4 mA, although the spec sheet suggests 10-20 mA). The output then yields a 5 volt signal (with a 5 volt Vcc), but with little drive capability (it would not light an LED). The output drops low when I interrupt the optical path. The data sheet says it will source 0.7 mA and sink 1.7 mA - so this makes sense. The data sheet recommends a bypass capacitor.

PCF8575 Signal Expander

The PCF8575is driven by two pins (an i2c interface) and provides 16 pins of somewhat bidirectional IO. Just the ticket if you are running short on pins and $12 on a breakout board from Sparkfun.

AD9835 Signal Generator

A bit pricey at $35, but Sparkfun sells a breakout board holding one of these, which can generate sine waves at from 1 Hz to 25 Mhz.

The SparkFun company sells many interesting surface mount chips on what they call "breakout boards". These provide connections on 0.1 inch centers and when appropriate add essential supporting components. A great idea.

JY-LKM1638 and TM1638 display modules

I picked up one of these in a junk pile, and they are well understood.

Litronix 1414 displays

I picked up a board with 4 of these displays (16 digits). The displays are actually made by Siemens.
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Tom's Computer Info /