0
cmnts

Get to know your kit

Before you begin, have you read How It Works?  Its not necessary to understand all the technical aspects of the design, but you should get a feel for how all the pieces fit together and what each part you are about to assemble does. OK, you read it? Then lets begin.

There are two circuit boards in this kit.  The Sensor Board is designed to fit on the typewriter's crossbar and detect keystrokes, while the USB Interface board is designed to control the sensor board and send USB commands to the computer.  They come as blank PCBs, so we'll need to solder the parts on, then connect the two boards.

0
cmnts

Size up the Sensor Board

Every typewriter is differently sized, so the sensor board is designed to be cut down to fit any typewriter's crossbar.  (If you are unsure where to find your typewriter's crossbar, see here.)Here, we decide where we need to cut it so it will fit onto the crossbar without bumping into anything.   

See the white boxes on the sensor board marked IC1, IC2, etc?  Try to cut right in between the boxes, but with a little margin for error.  For example,  you can cut in between IC9 and IC10, but keep your cut a little on the IC10 side, so you don't accidentally snip off any of the IC9 box's pads. 

You can only cut between IC boxes, so if you have to make the choice between cutting between, say IC8-IC9  and IC9-IC10, you want to err on the side of making the board too small.  That way it will definitely fit.  The contacts we will be adding later can reach outwards and make up the difference.

IMPORTANT:  The side of the board marked "USB SENSOR BOARD" is the KEEP side of the cut. Make sure you make your measurement relative to this side of the board.

Marking the size the board is to be cut down to.

Just snip it with scissors. Keep a little bit to the right of the line.

You can't see the white line in this image, but I've cut slightly to the right of it.

0
cmnts

Populate Shift Registers

Now that the board is cut to size, we need to insert all the shift registers into the sensor board, then bend a few of their leads so they stay in place.  After all the shift registers are inserted, we need to solder them in place. 

Try not to use too much solder -- if you do, the solder will wick into the holes that we are going to use for the feather contacts.  A trick that works great for me is to heat the IC legs, not the solder pads. If the solder does wick, don't worry -- it just makes inserting the contacts a little more difficult. If you can't stop the solder from wicking, put down the soldering iron and wait till after you have inserted the contacts to finish soldering the shift registers.

IMPORTANT:  The shift registers MUST be facing the correct direction -- with the notch on the chip facing the dot marked on the PCB.   You only have one shot to get this right, so please double and triple check the shift registers before you start soldering.

Note the direction of the notch on the shift register.Get all your ducks in a row before soldering.

I find that soldering from this side works best to avoid wicking.

0
cmnts

Mark the Contact Locations

We need to mark where the keys are going to fall when they strike the contacts on the sensor board. For every key, we are going to have to solder a feather contact to the sensor board in that location. The contacts are flexible, and you can bend them a few mm or so into exactly the right position, so really you don't need to be that precise with this step.

Just line up the sensor board in roughly the position you intend to mount it, then press it up so it is touching the keys. Then just mark every point that a key hits the board.

You can also do this indirectly with a ruler -- measure the total length of the array of keys, divide by (number of keys-1), and that is how far apart each mark should be.

Put a tick mark at the location of each key.

The lines are roughly where we will solder feather contacts.

0
cmnts

Create Feather Contacts

UPDATE:  In older revisions of the design, the feather contacts were to be made by hand rather crudely -- by flattening 1W resistor leads with a hammer.  However, in more recent versions of the kit, the feather contacts have been manufactured professionally by a metal fabrication company.  So, you can skip this step, since the feather contacts that arrive in the kit are ready-to-go, as shown here:

These tinned-copper contacts come with the kit.

0
cmnts

Solder the Feather Contacts

In roughly the same places you put the sharpie marks, you need to solder feather contacts, which will run up to the crossbar to meet the keys.  Do a handful of them, then try to wrap them around the crossbar in a trial run.  You may need to think about whether you push them into the hole from the top or from underneath. 

NOTE: If the hole you wish to put a contact in is already filled with solder, its no big deal. Just touch the iron to the periphery of the through-hole to melt the solder while you lower the contact through the hole with tweezers. 

NOTE2: VERY IMPORTANT:  Confusingly, Rev 1.0 Boards have two rows of holes on the board -- one row of holes shares its pads with the ICs; the other set of holes is further away from the ICs and serves no purpose. Make sure you solder the contacts to the set of holes that shares pads with the ICs (If you hold the board up so you can read the text that reads "USB Typewriter",  the row of holes you want to solder to is on the left.   Rev 2.0 boards don't have this confusing second set of holes.

You really really need a third hand or some Elmers Tack putty to hold the board.

These feathers come out of the top of the board. You may decide to have them come out the bottom instead.

0
cmnts

Flatten the Back of the Board

Its a good idea to snip all the leads on the reverse side of the Sensor Board, so it lays flat and there are no spiky leads sticking out that might accidentally prod the chassis and create a short. After clipping the leads to make the board flat, check that all the solder joints are still good. It might also be a good idea to cover that side of the board with gaffers tape.

Use nail clippers or clippers made for electronics.

0
cmnts

Assemble the Interface Board -

The interface board is pretty straightforward, compared to the sensor board. Solder all the parts onto the board as shown, using the Bill of Materials found here, and in the pictures below.  Pay close attention to the polarity of the parts indicated with arrows below (D1, D2, and C3) and the polarity of the ATMEGA168 microcontroller:

This is all the electronic parts you will need. Simple, no? Click this image to enlarge.

the arrows show parts that have specific orientations. The grey stripe on C3 indicates the negative lead. The black stripes on D1 and D2 should face away from the edge of the board.

The notch on the uC should face the marking that says "IC2"

0
cmnts

Test the Interface Board

At this point, you should be able to test the USB functionality of the Interface board before connecting it to the Sensor Board. Open up notepad and put your cursor in it. Then plug the Interface Board into the usb drive of your computer while holding down S1, the tiny pushbutton. You should get a message that reads:

USB TYPEWRITER
Rev 1.0
by Jack Zylkin
CALIBRATING, PLEASE TYPE THE FOLLOWING KEYS..... (or something like that).

0
cmnts

Create the Magnetic Sensors

The DIY kit includes several reed switches to sense the return carriage, shift key, and anything else that doesn't hit the crossbar. These are little switches that conduct electricity only when in the presence of a magnet.

Here is how to attach wires to the reed switches:

wrap some wire around the reed switch lead.

two wires soldered on in this way.

Now you want to insulate the contacts with shrink-wrap. I like to use clear shrink-wrap, since you can see the steam-punky looking reed switch through the wrapping. Just hold a flame close to the wrap, but not touching it. Here's a video:

0
cmnts

Connecting the Magnetic Sensors

This is the pinout for the Interface Board. Since the reed switches have two wires going to them, there are two holes for each key. Certain keys, like Shift, Alt, and Ctrl, have holes reserved for them. There is also a hole reserved for the chassis connection (see next step). Other keys, like spacebar and enter, can go in any other hole you please.

If you are not confident in your soldering, I would suggest you use a header here instead of soldering directly to the board. That way you can remove a wrongly soldered connection more easily.

What reed switches go where.

An example of a single reed switch wired in place.

0
cmnts

Connect to the Typewriter Chassis

If you look at the How it Works section, you'll see that there needs to be an electrical connection between the typewriter and the electronics. So we make a little loop or hook of wire with solder on it (to prevent fraying), which we will eventually secure to one of the many screws underneath the typewriter.

Make a little hook or loop out of a stripped wire and some solder.

The Chassis wire goes in the hole labeled "D5"

Heres an example of a chassis wire screwed into place on a typewriter.

0
cmnts

Test the Complete Assembly

You are done assembling the electronics! To test them out, open up notepad and maximize it (or similar program), then hold down S1 as you plug in the USB cable to the computer. A message should appear saying:

USB TYPEWRITER
Rev 1.0
by Jack Zylkin
usbtypewriter.com
CALIBRATING...PLEASE TYPE THE FOLLOWING KEYS:
a:

This is the system the typewriter uses to find out which key is which. Unscrew the chassis connection wire from the chassis, and tap it against one of the feather contacts (which should not be touching each other). The screen should now read:
b:

That means the typewriter has detected a contact and saved its location. Next comes c: And so on. Spot check all of the contacts to make sure they are soldered correctly. If the contacts are not responsive, or if the roll of letters advances without you doing anything, there is a problem. Recheck your connections for shorts, poor solder joints, and parts that are in the wrong way round.

DID YOU GET IT TO WORK? If so, move on to the Installation Instruction manual to plop it into your typewriter. If not, get a second opinion, sleep on it, then email me (in that order, please).