Close
0%
0%

25in24 Electronics Project Board

Re-vitalizing and modernizing a Radio Shack 65in1 kit for educational purposes - my DesignLab Residency!

Similar projects worth following
In the early 70's Radio Shack sold different educational kits so you could learn about electronics without taking a formal class. The 65in1 kit allowed the experimenter to put together 65 different experiments without any extra supplies. All of the circuits were wired using spring connectors and pre-stripped wires, and included excellent documentation. This kit started my journey on becoming a hobbyist, Electrical Engineer, designer and educator. My goal with this project is to produce a low cost, low entry level way for students to learn about electronics without the need of extra tools and supplies. Additionally, I am hoping to create well documented experiments so anyone can learn the basic concepts of electronic hardware. The name 25in24 pays homage to the original name - starting with 25 experiments while fast forwarding to the year 2024!

Phase 1:  My goal is to design five PCBs that include resistors, capacitors, active devices and various input and output components.  These will mount on a laser cut wood base similar to the original design, but smaller.  One of the issues with the original design is the springs would oxidize, and the wires would break.  I am planning on using standard breadboard jumper wires with headers on the board to make the connections.  

3D Parts.zip

3D files for Speaker grill / holder, light tube and temp tube

x-zip-compressed - 2.57 MB - 10/09/2024 at 23:50

Download

31-in-1 box cover.ai

Laser cut files for the mounting board. The Red means cut, the blue means to light trace, and the black means to raster

postscript - 440.33 kB - 10/09/2024 at 23:47

Download

31-in-1 Project Manual.pdf

A pdf of the manual - format is landscape 9 X 12 inches

Adobe Portable Document Format - 17.05 MB - 10/09/2024 at 23:41

Preview

Discrete-all_09-21-2024.zip

CAM file for fabbing Component board

x-zip-compressed - 339.15 kB - 09/23/2024 at 22:20

Download

Sensors-Outputs-09-23-2024.zip

CAM file for fabbing Sensor Outputs board

x-zip-compressed - 264.93 kB - 09/23/2024 at 22:20

Download

View all 9 files

  • Finally Done!!

    Tom Thoen09/23/2024 at 22:29 0 comments

    Well, after a lot of travel and other activities this summer I finally completed the project!  There are still a few files to add, but the schematics, board files, BOM, and instruction manual are now available for upload.

    I combined the smaller discrete boards into a single board - it will be easier to mount this way.

    Making PCBs:

    The .zip files can be used to order from JLC.pcb.  Nothing special about ordering other than choosing the colors!

    BOM:

    The Bill of Materials is an Excel spreadsheet - note that there are individual tabs for sub-sections and one tab for the whole project.

    Instruction Manual:

    The instruction manual is a .pdf that is in 9 X 12 format - it can be printed as a full manual.

    Other files / parts...

    Just added 3D print files for the speaker cover, and LDR and Thermistor tubes, and the laser cut file for the base.  

    Let me know if you have any questions on the build!!

  • Week 11 - Wiring Charts

    Tom Thoen06/06/2024 at 23:03 0 comments

    To verify that the circuits work I'm wiring each project, verifying they work, and creating wiring charts - tedious but necessary!  The experiment below is showing the current gain in a simple NPN transistor circuit.

    The original wiring charts from the kit - updating to the new connection pin numbers in Excel...

  • Week 10 log - PCBs done / enclosure

    Tom Thoen05/30/2024 at 21:39 0 comments

    The PCBs are finally finished!  I used different color solder masks to capture the look of the original kit.  I will be uploading the Eagle files and BOMS shortly.

    Tiffany has designed a panel and enclosure she is finalizing this week.  More photos coming soon!

    The manual is in process but will take some time as every project needs to be tested and documented for accuracy.

  • Week 7ish

    Tom Thoen04/30/2024 at 22:26 0 comments

    For creating the manual a number of illustrations are required.  Through the Design Lab I was connected with an Art Center student named Tiffany.  She is a fantastic artist and is helping re-create the original cartoons from the manual with a more modern feel...here is one of her preliminary ideations:

    So, it's time to work on documentation!  As before, my goal is to finalize the designs, build a number of samples and do some "in-class" testing.  Still a few weeks out on the manual, but making good progress!

    The board designs are finally completed and 25 experiments have been tested!  I'm going with different colors on the soldermask to pay homage to the original board.

    One of the more difficult aspects was determining the connection points for the jumpers.  The male wire pins tend to break after the wires are pulled out several times - so I am going with FF 20 AWG jumper wires.  

    On the board I originally was going to use regular male pin headers which are durable - however they are a bit sharp!  So, for now I am going to use shrouded headers (Molex) that at least will protect the user.  I feel like this is a critical point as the project reliability depends on how well the connectors work after multiple projects are tested and disassembled.

    I am hoping to have a fully functional prototype in about two weeks, with at least a preliminary manual...

  • Week 6 - Final project testing / PCB design

    Tom Thoen04/04/2024 at 23:02 0 comments

    Finally tested the last projects. 

    Revised the Sensors / Outputs PCB - using 3 pin headers to transition to SMT so they don't all have to be soldered manually.  Here is the final layout:

    My next plan is to solder up 3-4 of these boards and have people test them out for functionality / look / feel.

  • Week 5B - Next steps

    Tom Thoen03/28/2024 at 23:05 0 comments

    Next steps:

    • I still have a number of projects to test - documentation is going to be the biggest time challenge.
    • Modifications for the Sensors / Outputs board - need to spin up a new PCB.
    • Once everything is working create a BOM / PCB files / some kind of basic instruction document.  Ultimately this will be a big task to replicate the original manual from Radio Shack, which was very good!
    • Finalize design of overall box - most likely laser cut from wood.
    • Start Phase 2 - Digital logic circuits!

  • Week 5 - more testing!!!

    Tom Thoen03/26/2024 at 18:31 0 comments

    So far I've been able to get about 8 experiments working.  

    Lessons learned:

    The wire jumper ends break fairly easily, especially when I "rip" them all out of the board (memories of 5th grade!).  This also often leaves the pin stuck in the female header.  Also, the typical Dupont wire jumper pins are a bit small for the female sockets - they are a bit loose and don't make reliable connections and pop out of the sockets easily.  I did this originally to keep the sharp pins off the board, but now the plan is to replace the female sockets on the board with male .025" header pins.  The female to female jumper wires are much more secure on the header pins and the typical header pins I use are pretty robust.  Plus, they won't break!

    Maybe you think I'm overthinking this, but if this part of the board doesn't hold up, it will be very frustrating to the user!

    As there are a few other changes I'll be making I'll spin up another rev on the PCB designs.  The speaker sounds tinny as it's so small, so I'll probably replace the Solar cell real estate with a larger speaker...

  • Week 4 - Project testing

    Tom Thoen03/19/2024 at 23:16 0 comments

    Mixed success this week - I was able to get two projects working; however several others did not work.  Not sure if the issue is difference in components or not.  At this point I'll probably work on circuits *based* on the original projects but tweaked to work with my new hardware. 

    Project examples (need to create YouTube videos... :-o )

    Light meter:

    Siren:

    (Note that original speaker on PCB is pretty small and not very loud!!

  • Week 3 part 2 - testing

    Tom Thoen03/14/2024 at 23:14 0 comments

    Well, initial testing was more difficult than expected - took about five hours just to get a couple of basic circuits working.  Made a number of incorrect assumptions / mistakes including:

    • Assuming it might be differences between components (germanium vs. Silcon, transformer winding ratio, meter current)
    • Blaming the jumper wires (a bit old and janky)
    • Rushing too much when making the circuits

    Finally found out my resistor board PCB traces had not been routed 100%.  Yikes!  After re-soldering the board a couple of the projects are finally working.  Next step is to get a number of them fully tested and documented...

    Project # 1 test - tone generator :-)

  • Week 3 - PCBs in, soldering and assembly

    Tom Thoen03/12/2024 at 23:02 0 comments

    PCBs came in!  Thanks JLCPCB!!

    Soldered up the boards - Kino in the Design Lab Laser cut a cool outline in plywood that I'm using for the base for testing.

    Boards were soldered and mounted.  There were some clearance issues with the meter so some extra drilling needed to be done!

    I'm very happy with the layout - Later this week I will be working on testing using some of the original 65in1 experiments.

View all 11 project logs

Enjoy this project?

Share

Discussions

John Toebes wrote 3 hours ago point

Another question on the LED resistors.  

Looking at the LED for the 9V circuit, it is a 2.1V drop at 20mA.  Given the 9V supply, we should expect to see a 360Ω resistor, but the BOM specifies 1K.  That leaves the LED a bit on the dark side, but serviceable.

For the 3V circuit, the LED has a 2.05V drop at 20mA.  Given the 3V supply, the resistor should be 51Ω, but the BOM has it as 4.7K which makes for a really dim power indicator.  

For the big red LED, what voltage are you expecting to go to it nominally?  With the 100Ω resistor, there isn't much of a drop. 

Am I missing something obvious?
 

  Are you sure? yes | no

Ken Yap wrote 3 hours ago point

20 mA will probably light up the whole room. Modern LEDs are very efficient, and a few mA suffices these days. 20 mA in datasheets is a holdover from long ago when that was the max rating.

  Are you sure? yes | no

Tom Thoen wrote 3 hours ago point

Yup!  I usually shoot for 5-10mA max with basic diffused LEDs, but you have to watch out for the bright ones for sure!  

  Are you sure? yes | no

Tom Thoen wrote 3 hours ago point

So, for the LEDs I used non-diffused high-MCD rated LEDs with lower current for extended battery life.  Both are fine as far as I'm concerned - easy to see when on, but even if the switch is left on for a while it won't eat up the battery life.  I've actually used much higher brightness LEDS that work fine with less than 1mA!  That being said feel free to change it on your board if you want.  The 100 ohm resistor for the 10mm LED is basically chosen to prevent it from burning out if it's accidentally wired directly to the voltage source.  The value works fine for the experiments.  You can choose a different resistor also if you want.

  Are you sure? yes | no

John Toebes wrote 4 days ago point

A couple more notes from assembling the Sensors/Outputs board

1) For LED3 (XLM2MR01D) there isn't a flat side, instead it is the short leg of the LED.  Someone might spend a long time (myself included) looking for the non-existent flat side on that big LED
2) The 9V battery Resistor and 3V Battery resistors really need to go on the back of the board so that you can snug the battery holders solid to the board.
3) The footprint for the Thermistor (TH1) is a bit tight.  I'm thinking that you are expecting it to be raised up from the board a little, but I'm not quite sure in this case.
4) It might be worth adding to the BOM the screws for mounting the battery clips to the board as well as the standoffs for mounting the board on the base board.

  Are you sure? yes | no

Tom Thoen wrote 3 hours ago point

1)  Yes, 10mm LEDs often don't have a flat, or sometimes I've seen them with two flats!!  ALWAYS check these with a meter before installing if you are uncertain - if you have a diode setting that makes it pretty easy.

 2)  For the most part  I was trying to hide any components that were not directly part of the experiments, hence the resistors on the bottom of the board.

3)  Yes, the thermistor was maybe 0.2" off the board.

4)  Sounds good!  I'll see if I can revise the BOM this week; appreciate the second set of eyes!

  Are you sure? yes | no

John Toebes wrote 4 days ago point

Also, instead of putting the LED Resistor on the back of the board, why not hide it under the 9V battery with the other Resistor.

  Are you sure? yes | no

John Toebes wrote 4 days ago point

I found another oddity with the BOM for the 4 resistors on the Sensors/Outputs board

The BOM has
R1 - Meter Resistor 10K
R2 - LED Resistor - 100ohms
R3 - 9V Resistor - 1K
R4 - 3V Resistor - 4.7K

However the silkscreen on the board identifies them in the opposite order

R4 - Meter Resistor - 10K
R3 - LED Resistor - No value
R2 - 9V Resistor - No Value
R1 - 3V Resistor - No Value

I believe that the board labels are correct.

However, it might warrant an update to the board.  I've got a couple of suggestions if you do manage to update it.

1) The foot print for these resistors is narrower than the other board which used a .4 spacing (which is is the smallest slot on the resistor lead forming tool.  Please bump it up to .4

2) Don't restart numbering with this board, Make them R11, R12, R13 and R14 to avoid any confusion.

3) Make the footprint for the transformer have a spot for the extra output pin (going nowhere) and the solder down for the case.

  Are you sure? yes | no

John Toebes wrote 11/24/2024 at 15:57 point

Has anyone seen an online PDF of the original 65-in-one-kit?  I  found a version of the 160:1 kit at https://www.zpag.net/Electroniques/Kit/160_manual.pdf

  Are you sure? yes | no

John Toebes wrote 11/24/2024 at 22:06 point

I found the 75 in one at https://www.radioshackcatalogs.com/flipbook/m-science_fair_kits_75-in-1_electronic_project_kit_28-247.html along with a bunch of others at  https://www.radioshackcatalogs.com/science_fair_kits.htm but the 65-in-one seems to be awol

  Are you sure? yes | no

John Toebes wrote 11/23/2024 at 22:49 point

Great project Tom!  Thank you for all your effort on this! 

I've ordered parts and am about to build, but I've discovered a couple of questions about the parts from the posted BOM

1) SPK1 list a quantity 2, TX1 a quantity 3, and S1 a quantity 4 but I think that is just an excel auto increment and they all should be quantity 1.

2) SK1 is listed as being an SP570408-1 which has a 57mm diameter, but the 3D printed case is for a 50mm diameter speaker.  Should the part actually be SP500408-1 which looks like it would fit.  With the SP570408-1 speaker, it is larger than the screen printing on the board.  My choices at this point seem to be to order the smaller speaker or to tweak the model for the Grill to hold the larger speaker.  Is there an original model available to work from?

3) TX1 specifies a 42TM013-RC which seems to be the right physical size and is listed as a 11.486:1, but the silk screen on the board says 125:1 and the part has three taps on the secondary while the board is expecting only two taps.  Also, the board doesn't have any holes for the side tabs, so I am assuming you just cut them off.  Is this correct or did I somehow find the wrong part?  The specs of the 42TM013-RC part at Mouser seem to be appropriate for driving the speaker, but I want to make sure it matches what you expect.

4) (this is very nit-noid) The BOM lists C2 as a .02uF capacitor, but B32529C1223K000 is actually a .022uF cap.  Given that the range of a 10% tolerance includes both and 0.022uF is the standard, I am assuming that the BOM just dropped a digit.

  Are you sure? yes | no

Ken Yap wrote 11/24/2024 at 00:06 point

Hahaha, good catch about the auto-increment. Obviously 2 speakers are needed for the extension to stereo, and you can never be too careful, so 4 power switches. 🤪

  Are you sure? yes | no

Tom Thoen wrote 11/24/2024 at 01:29 point

Lol!!

  Are you sure? yes | no

Tom Thoen wrote 11/24/2024 at 01:29 point

Thanks John!  Glad you’re doing the build!  Thank you for the questions and catching the errors; I will correct them.  To answer your questions:

1)  Yup!  All quantity 1.

2)  I think the speaker should be a SP500508-1.  Unfortunately, I went through about six different speakers and lost track.  I will see if I can verify for sure…I know the print file / size is correct.

3) Whoops!  Yes, I didn’t have the turns ratio, it was the impedance ratio, my bad.   I’m only using the two outer taps on the secondary (cut the CT wire), and I cut off side tabs.

4)  I stuck with the original values from the original 65-in-1 even though they are not exactly the same as the parts.  Same as the 0.05 which is really 0.047uF

I'll get back to you soon hopefully on the actual speaker.

Thanks again!

  Are you sure? yes | no

John Toebes wrote 11/24/2024 at 15:56 point

Perfect!  I look forward to the updates but will be moving on to building in the next week.

  Are you sure? yes | no

Tom Thoen wrote 11/03/2024 at 15:45 point

Hi all!  If you happen to be at Supercon today I will be doing a lightening talk around 10am on the project.  Hope to see you there!!

  Are you sure? yes | no

Michael Gardi wrote 09/30/2024 at 14:13 point

So beautifully done Tom.

  Are you sure? yes | no

Tom Thoen wrote 10/09/2024 at 23:53 point

Thank you!  I hope others will be able to use the kit!!

  Are you sure? yes | no

rafununu wrote 09/24/2024 at 04:16 point

I received something similar made by phillips in the early 70s as a christmas gift. I played countless hours with it. It determined my future hobby and my interest for electronics that became my livelihood !

Btw, voltage isn't considered as a physical value, it's a current thru an impedance.

  Are you sure? yes | no

powiadam.ci wrote 05/06/2024 at 08:42 point

Can You create a different language info/tag ? For example Polish.

I thing power in center is better idea than on right.

  Are you sure? yes | no

Doug LaRue wrote 03/26/2024 at 02:47 point

Not sure if the original kit had plans for making a Volt meter but for teaching circuits and Ohm's Law, voltage and current meters are important tools to have. So besides making circuits, having enough components to make the play circuits AND have a volt meter wired up for the learner can explore the circuit would be great.

I was also thinking it would be handy having the xformer ratio listed under the part and maybe a "Power Sources" label added to the 9v and 3V outputs. Would also like to see the relay diagram but would be tough to fit that in the space. Hopefully it's on the side of the part.

  Are you sure? yes | no

Tom Thoen wrote 03/26/2024 at 17:26 point

Doug - great suggestions!  The original did have a current meter - I'm planning on having a couple of experiments with series / parallel circuits, etc where they can use the meter.  I'll definitely add the Power Sources label and turns ratio on Txformer.  I'll probably have enough room for the relay diagram too like the original.  Silkscreen layout seems to always takes more time than the original component layouts!! :-)

  Are you sure? yes | no

JammerX19 wrote 03/25/2024 at 16:46 point

I would love to buy this kit and use it as a build night activity for our ham radio club. 

  Are you sure? yes | no

Tom Thoen wrote 03/25/2024 at 17:48 point

Once I get everything finalized I'll post the build files.  However I'm also open to selling kits at some point - will let you know!

  Are you sure? yes | no

Doug LaRue wrote 03/25/2024 at 16:03 point

This kit is fantastic and as with others, brings me down memory lane as I had the 100:1 kit.

Currently trying to teach Middle School kids basic circuits and Ohm's Law using alligator clip leads and resistors and now starting a soldering lesson. Would be great to go in reverse on a kit like you have here. ie teach soldering first, make the kits and then use them to learn circuits! I like it better than the $50 Arduino Super Starter Kits I've used for small groups. Nice work.

  Are you sure? yes | no

Tom Thoen wrote 03/25/2024 at 17:50 point

Thanks!  Yes, that was my thought too - the soldering would be pretty basic - large scale pitch / through hole components would be an easy soldering project.  I also agree with the starter kits - the price point is good, but working with traditional breadboards is tough for younger kids.  

  Are you sure? yes | no

Doug LaRue wrote 03/25/2024 at 21:15 point

I love the breadboard kits but when teaching circuits and following electrical paths things get lost. Not to mention dealing with inserting components correctly and getting the jumper wires into the correct row. Gotta have a good grasp of a circuit and the way you did it, as did the springs, is ideal for the beginner. CS is starting to become a HS requirement and I would love to see basic electrical circuits be part of that.  I'll keep an eye out for your build files and thanks for sharing.

  Are you sure? yes | no

Robb Smith wrote 03/13/2024 at 04:28 point

Wonderful!  Seeing this is like bumping into a long-lost friend on the street.  Now all I need to be truly happy is a few Tab books; I read and re-read my copy of "Build Your Own Working Robot" till the book fell apart.

  Are you sure? yes | no

Tom Thoen wrote 03/13/2024 at 05:09 point

Glad it resonates with you! I feel like I grew up in a magical time as an electronics hobbyist. So glad there are websites out there that still have copies of magazines, catalogs, etc. I read BYOWR so many times - I think I still have my original copy!

  Are you sure? yes | no

Dan Maloney wrote 03/14/2024 at 16:27 point

I had that book too!

  Are you sure? yes | no

[deleted]

[this comment has been deleted]

Dan Maloney wrote 03/07/2024 at 04:17 point

Looked this up in the 1976 Radio Shack catalog -- $21.95. That must have been a fortune to my parents back then -- equivalent to $119 today! Wow!

Page 92 if you're interested: https://www.radioshackcatalogs.com/flipbook/1976_radioshack_catalog.html

  Are you sure? yes | no

Tom Thoen wrote 03/07/2024 at 19:45 point

Wow, that catalog was a trip down memory lane!  So many memories of things I could never afford when I was a kid.  The price on my 65in1 was $17.95 - makes me appreciate my Dad's willingness to help me get into electronics!

And one of the main goals of this project is to make something similar with a low cost point so they can be used in homes / classrooms, etc. without spending a lot of money...

  Are you sure? yes | no

Dan Maloney wrote 03/06/2024 at 17:23 point

Pretty sure this 65-in-1 is the exact one my parents got me for Christmas when I was about 11 or maybe 12. I hadn't really thought much about electronics before that, but I was on fire for the field after building that first circuit. That one present kicked off this whole crazy journey. Thanks Mom and Dad!

Thanks for the memories. Looking forward to seeing where this project goes!

  Are you sure? yes | no

Tom Thoen wrote 03/08/2024 at 15:14 point

I think this was about the same age I got mine too!  I found this one on eBay to show other friends / students how I started my path on learning about Electronics.  I miss these days of P-box kits and buying parts at Radio Shack.  My Dad also payed for my subscriptions to Popular Electronics and Elementary Electronics, which also had a huge impact on my journey too.  Looking forward to developing and sharing the project!  Cheers!

  Are you sure? yes | no

Similar Projects

Does this project spark your interest?

Become a member to follow this project and never miss any updates