USB - Typewriter

This is my version of the USB typewriter by jackzylkin : https://www.instructables.com/id/USB-Typewriter/


I also found good , very good, instructions at his web site http://www.usbtypewriter.com/category/installation-instructions


I would use those instructions to build this as they are very detailed but even so , I made mistakes. 

This instructable is to outline what I did wrong so others may not have the same trouble.

Basically I bought the conversion kit from jackzylkin Etsy store and got a typewriter from a garage sale.


I followed the instructions and after quite a bit of time and effort I ended up with this:

I ordered the conversion kit from the Etsy store , printed out the Instructable and bought a typewriter at a garage sale.

After measuring the sensor board to fit the cross bar, I cut the sensor bar.

However I failed to understand that you MUST cut between ICs.  I did not  but fortunately I was able to make a second cut and still have enough spaces left for the contacts.


Also:

Depending on how you actually do this, accurately marking the sensor board was not critical.   It is critical that there be enough spots in the board to solder in a contact for each key.  There will be room for moving the contacts around a bit so they line up with the keys. .

This step is not entirely a mistake but I did not have good success trying to do this the way the instructable suggests..

Basically, the kit came with a lot of resistors which you cut the leads of and then hammered them out flat.  This was a lot of work and eventually I could not get it to work properly.   HOWEVER , I see the newer kits come with a supply of contacts which should make a huge difference in being able to complete this step successfully.

Basically the idea is that you will insulate the typewriters cross bar with tape and then wrap one of the contacts around the crossbar so that there is  a contact for each key.    When you strike the key, the circuit  will be completed through with the contact.   Each key will have only one spot on the sensor board where the circuit is completed and this will map to a letter.

I could not get the resistor contacts to stay in place so I tried a couple of other ideas.

1.  First I took a small dowel and drilled a hole for each contact, wrapped bare copper wire around and soldered it in place.  Then I wanted to attach the dowel to the crossbar , lining up the keys with the copper wire.  This almost worked but I found the keys would raise the crossbar before contacting the copper wire and I could not find a way to overcome this.

It also was to heavy causing the mechanism which advances the ribbon to not work.  But it did make lining up the keys with the copper wire easier.


2. As I did not want to waste all the work done to that point , I tried moving the wood dowel to the other side of the crossbar but this too was not successful.

I finally went back to the original Instructable and basically did what was done there.  I did use short lengths of bare copper wire wrapped around the crossbar instead of the resistor leads.   This worked well as I could wrap around twice and the tighten by twisting them.


HOWEVER:
2 mistakes occurred with this method also;
1. If I tightened too tight they would eat through the tape and make contact with the crossbar.  This would make calibrating the keys impossible.

2.  In a couple of cases when soldering the copper strips to the sensor board, I must have touched the iron to the insulation and burned a hole through which would provide a spot for the wire to again contact the crossbar

Between the original Instructable and the info on the web site, everything else went pretty smoothly.




This was a difficult project but I want to do another soon.  I still think I can think of a quick easy and secure way to connect the contacts ro the crossbar but for now I am am pleased with the result.