A New Walther Free Pistol Replacement Electronics Board

[Bob LeDoux]

I have developed a replacement circuit board for the Walther Free Pistol. The board includes dry fire option.

I’m looking for ideas as to the best way to make this information available to others. I am unwilling to sell parts or boards due to liability issues. I am willing to provide my assistance to others as questions arise.

The information is freely available for others to use. The material could also be used to develop a new single shot target firearm.

The design is specifically tailored for construction by electronics novices. It uses through hole construction, no tiny surface mount parts. The article is detailed to take the user step-by-step-through construction.

The data is in six files: The pictorial Walther article, 23 pages, describes my experimentation, design and construction of the replacement circuit board. I have two circuit board files; a single sided board for home construction and a double sided board for factory production. The board makes use of a PIC microcontroller so assembler and hex files are available.

I have consolidated the files in one zip file for easy download. File size is about 500kbytes.

[Russ]

Great! Thank you Bob!
How to get it build? I need one.

[Bob LeDoux]

I expect a number of individuals will want replacement boards. This will make it possible to order multiple blank boards for a low cost, perhaps less than $10 each. The components on one board cost less than $20.

By combining skills it should be possible for a group of persons to get these put together.

Of course, I have no complaint if someone else wants to make copies of my board. However, that person has to accept liability and may need to provide support for the project.

The circuitry is simple, construction is simple, the software is simple. But it may take skills from several people to bring all these pieces together. I have attempted to provide a depth of detail so others can understand the tasks.

If you've ever soldered a circuit board project together you should have the construction skills. The board files permit the boards to be ordered from a vendor at low cost. The software requires someone to put the program into the PIC microcontroller. This is a task being performed daily by tens of thousands of kids and professionals.

My only other concern is the possibility of being overwhelmed by requests for assistance. (One can hope.)

I've attached a photo of my new board below my original factory board.

[Russ]

It will be cool to see this thing working again.
I’m not big in electronic DIY projects. I’ll be happy to pay for the product.

http://midwestacademyconsulting.files.w ... 010010.jpg

[LukeP]

Hi Bob,
i'm interested in circuit board.
I wish to put an electronic trigger to my toz, to release firing ping need 650 grams of force, how function on Walther? solenoid directly strike cartridge or simply release the firing pin?
Please how many batteries are requested by circuit, and do you have access to solenoid small and powerful enough to do work above explained? (13mm diameter, push type, at least 700 grams force at 1mm travel) i think it's similar to morini and steyr one. Hard for me is find the solenoid in small number, 4-5 to make test; found a chinese fabric but require 10000 items at time!

If possibile i wish to buy and build the board, or at least know more; as you made also my result will be published.
Thank you,
best regards,
LukeP.

[Bob LeDoux]

Hi Bob,
i'm interested in circuit board.
I wish to put an electronic trigger to my toz,
best regards,
LukeP.

Have you looked here?

http://toz35.blogspot.com/2011/10/elect ... anics.html

Igor has done exactly this using a solenoid from a Steyr LP10 operating at about 16 volts.

My circuit is powerful as it operates at 150 volts and accelerates the firing pin into the primer in the distance of 2.5mm. The Walther coil is about 20mm in diameter.

The voltage can be brought down by changing a value in software. So my board would work for your type of application.

Your pistol has a very low "duty cycle." This means shots are fired at least 30 seconds apart. A high duty cycle rated solenoid can be operated at a much higher voltage when used at a low duty. This is because heat builds up in a solenoid when the duty cycle goes up. Heat buildup is a limiting factor.

For your application look for a lower voltage solenoid. Even a 6 volt component should work at 75 volts. Experiment with low cost surplus market solenoids.

The physics state: when the voltage is doubled, four times as much energy is delivered from a capacitor discharge circuit.

My board uses a standard 9 volt battery.

[LukeP]

Thanks Bob,
i'll start reading your material!
Yes, i know Ruig's work, my biggest problem is to find the solenoid, Steyr didn't sell separated from the trigger.
My intention with Toz is only to have a electronic firing pin release, not to strike directly the rim, but it's interesting your way because virtually reduce a lot firing time: by data a small solenoid can travel 1mm under 5-6ms.
Thanks again,
LukeP.

[Bob LeDoux]

The files .pcb are the circuit board files. They use the free ExpressPCB.com software. The single sided board is printed on page 23 of the article. It can be used to etch a board at home. The double sided board is intended for purchase of boards from ExpressPCB. Details are in the article.

These files can be modified for individual use.

The .hex file is the compiled file to load into the PIC microcontroller.

[Bob LeDoux]

I have also placed my files on the Free Pistol group where you can download individual files:

http://sports.groups.yahoo.com/group/Fr ... w%20Board/

A login is required.

[Peter Skov]

I Just bought a Walther FP1 inspired of your DIY projekt.
Gave around 180$. Is is Currently working.
I'm looking forward to getting i, which probably will take a couple of months due to registrations here i Denmark.

[Bob LeDoux]

Thanks for the feedback. I'd like to know who is making progress on a replacement board. Contact me at the email on the download file.

I've received comments from shooters who are not comfortable moving into the electronics arena.

My suggestion is to contact a local "ham" radio operator. That person should know someone local who is willing to "Elmer" a new electronics project. Elmer is the name hams give a person who offers to mentor in the field of electronics.

Bob, N7SUR, Advanced.

[IPshooter]

Bob,

It's great that you've given hope to Walther FP owners. While I don't own a Walther, perhaps you will take on an even bigger problem - repairing failed Morini electronics. Will you do so, please??????

Stan

[jbshooter]

Hi Bob,
I've got the FP with the later board, serial 1262.
I get a misfire about once every 20 shots, I think because of a weak firing pin effort.
Did this also happen with the earlier board or did the earlier board fail to function altogether?
I'm happy to send you any photo's of the board.

[jbshooter]

Hi Bob,
I've got the FP with the later board, serial 2160.
I get a misfire about once every 20 shots, I think because of a weak firing pin effort.
Did this also happen with the earlier board or did the earlier board fail to function altogether?
I'm happy to send you any photo's of the board.

just changed serialumber to 2160

[Bob LeDoux]

Hi Bob,
I've got the FP with the later board, serial 1262.
I get a misfire about once every 20 shots, I think because of a weak firing pin effort.
Did this also happen with the earlier board or did the earlier board fail to function altogether?
I'm happy to send you any photo's of the board.

I'd like to see a picture of the board, while mounted in the pistol. In my article I note that I have not been able to examine a newer Walther. My efforts to help newer owners makes assumptions about the power switch assembly and board mount.

The board is designed so the "charged" light needs at least 90 volts to light. A weak battery may light the neon bulb but not provide full firing voltage. So if you have misfires, first replace the battery. If a new battery doesn't solve the problem then,

Misfires may be due to gunk. I suggest cleaning the pistol firing pin. Remove the grip. Remove the sight bar assembly (part 2). Both are mounted with a 4mm hex bolt.

Then rotate the breech block behind the firing pin, part 37, a quarter turn and pull it out. The firing pin and return spring, parts 36 & 35, will drop out. Wipe the firing pin clean and run a pipe cleaner through the firing pin hole in the breech to remove any powder crud.

Reverse the order for re-assembly. I've seen no recommendations for lubrication of the firing pin. However, there is a hole in the breech block end to pass air. The grip also has a hole to access this port. This suggests to me the firing pin was intended to be lubed.

If this doesn't solve the problem I'd check the charge voltage level on the large capacitor. On my early model, and my replacement board, this is about 150 volts when charged and ready to fire.

I've attached a factory parts list to which I referred, above.

[jbshooter]

Thanks Bob,
I've got this picture as well.
I've got loads of photos on my other computer. I will try and get them off to you later today.
regards
John

[Bob LeDoux]

Bob,

It's great that you've given hope to Walther FP owners. While I don't own a Walther, perhaps you will take on an even bigger problem - repairing failed Morini electronics. Will you do so, please??????

Stan

I had to buy a Walther to make a replacement board. Commitment to the Walther was because all electronic support for the pistol has ceased.

I can't afford to buy other pistol models for the purpose of making replacement boards. This is especially true when those manufacturers' are still supporting their products.

If someone wants to share a dead board from another pistol I'd be interested in examining it further.

[jbshooter]

Here are the photos Bob.
Please note that I think I might have had the large capacitor changed when i had the wires extended. The wiring was a bit stretched and frayed when I bought the pistol so I had my local radio engineer repair them and I think he did the cap at the same time.
The cap says Photo Flash 330V 70uF on the underside.

[Bob LeDoux]

Here are the photos Bob.
Please note that I think I might have had the large capacitor changed when i had the wires extended. The wiring was a bit stretched and frayed when I bought the pistol so I had my local radio engineer repair them and I think he did the cap at the same time.
The cap says Photo Flash 330V 70uF on the underside.

I think your big capacitor is too small. I'd suggest using a 100uf cap from a one use disposable camera. The Fuji camera uses a 100uf, while the Kodak uses a 120uf. Either would do.

Neither of the factory diagrams I have show so small a cap. That could result in a unreliable ignition, even if the rest of the board is working properly.

What surprises me is your board design. My best information is that Walther produced a board in 1986--a through board, and a surface mount board in 1989. My factory board, displayed earlier in this thread is an early board. But it has a relay, which is not present in your board.

This is troubling because it means there may be another generation of boards out there. If Walther was forced to use at least three different board versions they had electronics problems that were difficult to resolve.

[jbshooter]

Is my serial number 2160 a later build? Does anyone know?
Also, does anyone in New Zealand have a Walther FP they would like to sell?
Even a left hand one.