Building a toy control panel

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Building a toy control panel

Postby caramellcube » June 20th, 2014, 6:53 am

Hi all,
I've been asked to build a toy control panel, so I thought I'd post the build here to get some ideas and advice. I want to make this something that lasts, has a load of functions, and is safe enough for all ages, so after a number of trips to car boot sales I managed to put together the collection of parts shown. I have a few ideas for functions to add, such as...

a 4017 based 4 colum counter wired to the rotary phone dial,
a 555 & 4017 based ring of cycling leds with the frequency controlled by the throttle,
a binary rotary switch wired to an RGB light,
some type of motorised crane or arm,
an ammeter wired to the main power supply to show how much current the whole panel is using,
sound and light effects... lots of them.

There's a lot of work to do to get it all built, but for now I have a problem with the tandy 12-led game. The buttons are not very responsive, it takes a fair amount of effort to push them and have them register. The contacts seem to be metal springs mounted above circular plates, Is there a known way to repair or mod these?
Attachments
had_tandy_led_game.jpg
had_components.jpg
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Re: Building a toy control panel

Postby lastchancename » June 20th, 2014, 7:28 am

My suggestion is to rplace thse switches with small TACT style buttons, or something else that has a suitabk profile and is child-proof.
The smaller TACT switches may fit in the existing space as-is.
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Re: Building a toy control panel

Postby caramellcube » June 21st, 2014, 1:08 am

Thanks for the suggestion, I just tested it with some tactile buttons and they click with far less effort than the springs, it looks like it'll be difficult to get them precisely alligned with the plastic rods that are supposed to push the springs though, and I'm not sure how to securely mount them onto the board. The main problem is the springs extend out from where they're soldered to make contact with the plastic rods, while the tactile buttons don't. I might be able to build some type of adapter out of stripboard, or use thin wires and hot glue, but I'm not sure how durable that will be.
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Re: Building a toy control panel

Postby Retroplayer » June 23rd, 2014, 3:51 pm

They aren't responding well anymore because the plastic rod has deformed them. Fixing them means re-bending them. Place the bend right at the point the plastic rod makes contact. Also be sure to clean both surfaces with a pencil eraser to remove any oxidation.

As far as lining up tact switches, I see a great deal of wear on the metal springs where the plastic rods have been rubbing. Dead giveaway where they are going to land.

Is it possible to use the tactile switches with the longer button and cut the plastic rods off and glue your new post to the switch button?
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Re: Building a toy control panel

Postby caramellcube » June 25th, 2014, 1:14 am

Thanks, I'll try rebending and cleaning the springs. I don't think I can glue the tactile switches to the buttons without sealing the unit closed once the glue dries.
Attachments
panel-spring.jpg
The spring contacts, with and without tactile switch.
panel-buttons.jpg
The top panel interior showing plastic rods that push the spring contacts, and holes for the LEDs to shine through.
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Re: Building a toy control panel

Postby Retroplayer » June 27th, 2014, 9:44 am

If you do want the tactile switches, I would look at the reverse side and see if you can drill holes for the leads of the tactiles that would line up with the traces (or allow jumpers to the traces.) You only need to use two pins of the tactile switch, so worth looking at. I did this with a cheap chinese USB gamepad. Just use a piece of perf-board as a drilling template

I imagine lining the tact switch up with those metal buttons would have them lined up with the posts. The only issue I see is that I don't think those plastic posts look very accurate. I wouldn't trust them to land on the tact button every time unless you used a bigger tact switch.
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Re: Building a toy control panel

Postby caramellcube » July 27th, 2014, 2:34 am

A bit of an update, thanks for all the advice but unfortunately the LED game doesn't seem like it's going to work in this. It's too big to fit alongside the other parts, and when I tried soldering a tactile button in the copper track detatched from the board. I think I've got that fixed with some superglue but I'm planning on replacing that part with a trellis instead now. It'll increase the build time but it's got more light up buttons in a smaller space.

On a more positive note, the power supply is built and working. It still needs a bit of work to make it safe and tidy but it powered up the music panel and all the voltages seem to be stable.
Attachments
had_psu.jpg
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Re: Building a toy control panel

Postby caramellcube » August 20th, 2014, 6:37 am

I could use some advice with this part. The photograph below shows what I'm planning on mounting behind the TV facia. The board with the red LEDs is an old Wizard game that should be fairly easy to install (it just needs 1 power line, 1 speaker and 4 buttons connecting), but the white LEDs I'm having problems with. They're supposed to show numbers by taking each bar as a single digit, so the right hand bar is units, the middle is tens, the left is hundreds. The input to the system is going to be a rotary phone dial, so numbers can be dialed in and added to the total. It's supposed to be a graphical representation of basic maths.

The way I was going to do this was to have 3 4017 decade counters. Each runs it's own bar of LEDs, with the 0 output unused. The units is clocked by the dial, the tens is clocked by the units, the hundreds clocked by the tens, so that as each bar rolls over it adds 1 to the next bar. I'll also be adding a reset button.

Here's the problem, The chip I've been testing always starts at 1 but resets to 0, so how do I do this without having it start at 111?
I take it I can't use the /10 output to generate a clock signal or the numbers will be in the wrong order (1,2,3,4,15,16,17,18,19,10,11...), but if I use the 0 output, won't that add 1 to the next line when the reset button is pressed?
Any advice would be much appreciated.
Attachments
LEDs.jpg
WIP of the innards of a display.
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Re: Building a toy control panel

Postby Retroplayer » August 31st, 2014, 1:29 am

Use a power on reset IC to cause a reset after a very short (not noticeable) delay?
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Re: Building a toy control panel

Postby caramellcube » January 5th, 2015, 2:11 am

Just thought I should update this thread, thanks everyone for the advice, the panel is finished and apparently getting lots of use. I ended up leaving the counter module without any error correction, but it has selectable manual and automatic input modes (either a rotary dial and button, or a 555 timer controlled by a joystick throttle).
The main thing I learned is to find a good way of connecting to the power bus, those terminal blocks worked but they're not fun to wire up when you keep adding new systems. Anyway, here's a photo...
Attachments
had_panel_lit.jpg
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