You are one of two types of people:
Type 1: I'm going to make my own. Its a simple circuit, how hard can it
Type 2: What are you mad? Do I look like I was dropped on my head? Tell
me where to buy one now you muppet!
Type 1s: read on and check out the links below
Type 2s: try these links
Easy home build solution
My latest interfaces are based on a readily available pre-made circuit
from active robots. It can be purchased here
It is powered from the USB port so only the ground and the data line
from the ALDL port need to be connected. The Rxd and Txd pins must be
connected together and connected to the ALDL data line and the ground
from the ALDL must be connected to the ground pin on the circuit.
Drivers for it can be found here
Or if you enjoy soldering
My first circuits were based on Ian Levy's as, at the time, it
only circuit I knew had worked with an Elan. His circuit can
be found at http://www.syntaxis-technology.co.uk/lotus/hardware.html
In fact any of the 8192 baud ALDL circuits out there should work.
Below are stripboard layouts of a slightly modified (IC1 changed to
MAX233/MAX232, output voltage changed from Vbat to 5V and the input
threshold level lowered slightly) version of
the circuit mentioned above. I've built all these designs and they
worked for me.
If you copy any you take your chances. If your computer catches fire,
house burns down, your car explodes, your significant other leaves you
your dog moves next door I'm sorry but that's it.
MAX233CPP circuit version 1
Ok just a bit bigger than it needs to be.
MAX233CPP circuit version 2
Slight changes in comparator voltage thresholds, made more
space opened to allow regulator to be leaned over a little more.
MAX232CPE circuit version 1
Cheapest of the three in terms of components, compact -
prototype pictured - extra capacitor included).
The 'x's on the diagrams indicate where tracks should be cut. All the
tracks between the legs of the ICs should also be cut.
For the 7805 regulator pin 1 (input) goes on the 12V rail (track 2),
pin 3 - the middle pin for some reason - (gnd) on the ground rail
(track 3), and
pin 2 (output) on the 5V rail (track 4). I think
its the same
the LM2931A - check. So, as you look at the figures above, the heatsink
of the regulator should be on the right.
All the bits are available from RS
I inked in the track numbers and the component positions on
the board before I started soldering. Use a small tip on the iron and
don't use one thats too powerful - its easy to fry the Si bits (use
for the ICs). If you aren't confident at soldering practice on a spare
bit until you can put joints on the board quickly and reliably without
crossing tracks. It doesn't have to be pretty. Once you've finished
it thoroughly visually and if you can with a meter for errors and
Once you've made it the acid test is to power it and connect it to the
PC. Start hyperterminal set it to the COM port you're connected to and
type in some characters if they echo it works! If not unplug and check