Insert Coffee - Circuit problems

[Silas (son of Silas)]

I dont trust these things not to pull out if the cord gets pulled from any angle but straight exposing live wires! I'd prefer the power supply entry things with 2 screws holding them! Just my 2 cents!

Interesting. IEC connectors have been the industry standard for literally thousands of appliances including PCs, workshop machinery and kitchen kettles. Short of cutting the lead with a knife there's no way that you can expose live wires. If you pull the lead out, the contacts are completely shrouded way up inside the plastic lead. (see pic below). The pins in the previous photo I posted are in the socket, not the lead, so when they are exposed they are not live.

The 90 degree leads like the one in the pic are also almost impossible to pull out without grasping the plug itself and pulling perfectly straight. Any lateral force has almost no effect unless you pull so hard you snap the cable, but then thats the same regardless of how the cable enters the machine.

[Nacimroc]

I meant the female part can pull out! That is the bit that lead fits into, the permanent piece in the cabinet! It has a lip to stop in going in but not pulling out! I bought one for my cab but I won't use it!

[polaris]

I meant the female part can pull out! That is the bit that lead fits into, the permanent piece in the cabinet! It has a lip to stop in going in but not pulling out! I bought one for my cab but I won't use it!

it looks like the one in that pic is for mounting on metal panels, it has clips that hold it in place, for wood you can get ones with screw attatchments i'm sure

[EightBySix]

Ok, so got a decent workbench now. I've started to get back on track. Been looking for a particular Dell monitor - E172 - same as one we have at home becuase I know it has a wide viewing angle and bright colours. One turned up on ebay that was scratched and had pressure marks - neither of which I particularly care about, esp since most classic games are on a black background, so they wont really show. Got it for £9.99 (ok - same for postage, but still...)

Could see no obvious way to get the case off, but a bit of Googling revealed some small slits to poke a flat blade screwdriver into and pop the cover off. See any scratches? 


It was thinner than I had hoped for - should leave me with a bit of room inside the table:



Now I have the monitor, I can work out a final design based on those dimensions, and that of the joystick (thanks for the advice there, by the way), so the table top will be as thin as I can make it.

[jmike]

Very cool project. Can't wait to see some progress pics.

Any chance you have the link for that touch sliders for volume control thingy? Never seen anything like that before.



 

[EightBySix]

Any chance you have the link for that touch sliders for volume control thingy? Never seen anything like that before.

I found this when googling capacitive touch sensors. It's a design example rather than a product you can buy I'm afraid. If you understand more than 10% of it, then let me know 

[EightBySix]

After more procrastination than is good for me, I think I have decided on my design.

I've tried to plan it out as well as I can, because I have to get the wood delivered, which means a cutting list. I can't just nip down to the local DIY store if I get it wrong. The control panel arrangement is going to be tricky though, so I'm going to prototype it in cheaper wood.

A prototype controller means it's time to buy an encoder, but I was a bit suprised at the cost of them. It looked like it might be the most expensive part of the project, which didnt seem right. I tried a keyboard hack, which turned out a mess, with no guarantee that it would work properly either. Whilst googling though, I came across a very helpful website by a guy who made his own. It involves an extra piece of kit to program the microcontrollers, but as I can pick one of those up for less than an encoder, I thought I would give it a try. I'll need one anyway for some of the other bits of electronics that are a gleam in my eye at the moment. So after a bit of online shopping, this arrived on my mat:

I think I have a steep learning curve ahead  especially after the mess I made soldering the keyboard hack - but that's whats fun about all this

So... I'll try and put it together, program the encoder and I'll let you know how it goes.

[jholman76]

That looks like all sorts of fun....

You could always go on deal extreme and get a cheap USB pad to hack. There is a thread out there that I posted in that details how to do it.

joe

[emphatic]

So, I don't understand where the wires will go from that controller box -> inside your cabinet. But I guess you've planned it somehow.

[EightBySix]

  ...wires? I knew there was something 

I'm either going to embed a ribbon cable in the hinge - like on a laptop screen, or send them through a hole in the side of the panel. The prototype will show me the way hopefully.

[leapinlew]

I love the idea of doing something cool with the coffee table, but the main problem I have is an elegant solution to get power to the middle of the room.

[emphatic]

Ribbon cable sounds like a nice plan. 

[rablack97]

http://www.lizardlickamusements.com/images/for_sale/electrical/power_entry.jpg



LizardLick.com

or

mouser.com ( this place has everything you can think of electrical)

both ship international
(This may be a bit late, i didnt see there was a page 2 when i posted this, oh well, hope it helps anyway...)

[Bender]

I love the idea of doing something cool with the coffee table, but the main problem I have is an elegant solution to get power to the middle of the room.

Base it on a laptop and run it off the battery (the newer ones have like 8 to 10 hours of runtime)  then you just need to plug it in one in a while to charge it. That way the power cable wouln't be there most of the time

or just drill a hole in the floor under one of the legs and feed the power cord through there (I'm only half joking, I might actually do something like that)

After more procrastination than is good for me, I think I have decided on my design.

Love the fold out CP design!

[EightBySix]

Good news first - I've been busy putting my microchip programming kit together, and ended up with this:

I really enjoyed doing it - real 'tongue in the corner of the mouth' concentration stuff. I made a much better job of the soldering since my attempred keyboard encoder hack. Thanks to some tutorials I googled.
Bad news - It doesn't work! I checked out the support forum, and it seems you have to be careful with the com ports on modern motherboards, as nowadays they dont use an actual RS232 chip, but emulate one, and not all work with the programmer. I put it on an older machine and stil no luck. To be honest I would have been amazed if it had have worked 1st time around without some assembly mistakes.
Turns out though, and this is where I failed to do my research properly, that the kit wont program the kind of chips I need for an encoder - I need one with more pins, unless I compromise on the number of inputs I can support.
I'm going to have to get another to allow me to make what I need. I'll still see if I can fix the one I got as a learning exercise, but mucking around with it is stopping me from getting on to build my CP prototype.

I had an idea whilst building out my sketchup model. I was making a bezel texture and thought why not use a veneer, to match the table panels. Only drawback would be the 16x2 matrix for the underglass display look a bit out of place. Then I remembered a clock I once saw on a gadget website:


So I thought I could do somthing similar with a differerent, brighter kind of LED, like this:

After a score on eBay, I'm on the way to a hidden 'frond end' / status display... Here's a sneak preview :-)

Its just a shame I got lost after potential dividers in electronics at school ;-) ... Onwards and upwards...

[abzman2000]

As far as the encoder goes, this is where I can chip in, try a combination of an arduino and some digital multiplexer chips.  The reason I say arduino is because it can emulate a pc keyboard already, well, kinda.  Someone wrote a library to interface the arduino to a pc and have it pretend to be a keyboard, and it's only a few bits of hardware.  Digital multiplexer chips allow communication of more inputs on a single pin, so you can expand the number of usable pins as much as you need.  Check this link for how to set up multiplexer chips.  The keyboard interface is easy too, this link documents it fairly well, so with a little bit of coding you could set up macros, shifted keys, turbo buttons, or anything else you might want, but it would be completely independent of the computer. 

[Blanka]

I don't get all the fuss about the costs. A basic encoder is like 25 euros, and a gamepad-hack (keyboard-hacks sucks) is maybe 5 euro/player. This prototyping board is way more complex.
With arduino, you can also use resistors to multiplex. Then convert the analog signal to the keys pressed. But Arduino is 25 bucks as well.

[EightBySix]

I don't get all the fuss about the costs.

It's not really the money - I'm going to need to get my head around this stuff for some of the other bits of the project I'm planning anyway. So when I get up to speed, the keyboard encoder should come along 'for free', plus if its my own I can get it to do some non-standard stuff too I think I'll be needing.

As far as the encoder goes, this is where I can chip in, try a combination of an arduino and some digital multiplexer chips.

Chipping in (ha - no pun intended  ) is very welcome. Thanks - reading up on multipexing now. When I was originally reading up on this stuff I looked at the arduino, but went the PIC route because I thought that I would need an arduino board for each little project. I didnt think I could just pop the chip our once I had finished the coding and solder it into something more permanent. As I learn more though, I guess there is no reason why that wouldn't be possible...

[abzman2000]

As far as I know the only things you need for a really bare-bones arduino is a power source, a crystal, and a reset button.  you could use a usb ttl serial cable to program it, or you could just pop it in the arduino board, load the program and drop it into the project.  Here is the really bare-bones schematic, or you could just google for it to get some other people's ideas on it.  As far as programming the chips, I would burn the bootloader with the usbtinyisp, and upload the code with the usb-ttl serial converter cable (takes the place of the serial chip on the arduino board).  The arduino is just a micro-controller with a boot-loader so you can use simpler code to program it rather than learning the more difficult micro-controller code.  You can buy these micro-controllers (atmega 168, or 328) pre-programmed from this guy or over at sparkfun.  Or you could buy the blank ones from any electronics website that deals in them (digikey, mouser, etc...) and get the boot-loader burned with the usbtinyisp, but it's not much cheaper than buying them pre-programmed. 

[EightBySix]

I've been lurking around eBay for ages for a linear actuator that is quiet, and has the right stroke length. I finally snagged one of these:

It should open and close the table fine, but I'm concerned that it's a bit over powered (this is one of the less powerful ones) as it can push 600Kg! Does anyoe have any thoughts of some kind of safety device to stop it closing should little fingers / coffee mugs be in the way? I'm thinking an IR LED/Sensor pair, or maybe a pressure sensor on the inside edges of the table leaves....

[Rick]

This... ...is slick.  I love it.

[JustMichael]

Have you thought about using a 2way mirror for the top of the coffee table instead of the sliding wood panels?  While the monitor is off the top would just appear to be an ordinary mirrored top.  When the monitor is on it will shine through the mirror.  This would also protect the monitor from spills.  With the sliding wood top there is a gap in the middle for a spill to sneak through.

[drventure]

I love that "Led behind the veneer" idea!

Cool stuff! and an excellent way to do a coffee table cab.

[EightBySix]

Have you thought about using a 2way mirror for the top

Actually no, I hadn't thought of that. Wouldnt really fit in with the traditional look I'm going for though. Hopefully, I'm covered in terms of spillage with the design I chose.

I had a thought regarding a safety device. Some sort of sacrificial linkage with the actuator that would break relatively easily if all the electronics went wrong. Maybe a strain gauge on it to hopefully stop the motor before it came to that. This kind of actuator is used in hospital beds / door openers etc. They must have some sort of safety mechanism too right? Anyone know anything about it?

[EightBySix]

Reading Konky Dong's post inspired me to just get some tools out and get going. There is only so much you can plan for, and better to fix things on the way than never have an idea leave the drawing board.

Just beat the 1 year anniversary of my last post... Since then we have redecorated and the table will now have to fit in with oak decor. That blew the price of my table out of the water, so it was kind of on hold. Part of the redecorating though was to build a little computer desk, which I used oak laminated mdf for. There was some left so out came the jigsaw.

I've changed the design though. I couldn't see a way to make the joystick in a drawer idea strong enough, so I have gone with this instead:

The whole centre panel sinks into the body of the table when it closes.

Progress pics as soon as I manage to get them of an uncooperative phone...

[Yvan256]

What if you put just enough space for the buttons under the sliding panels and use The Link for the joysticks?

[Nephasth]

What if you put just enough space for the buttons under the sliding panels and use The Link for the joysticks?

That's good idea. Didn't even know about The Link before. Too bad preordering is over.

[Yvan256]

What if you put just enough space for the buttons under the sliding panels and use The Link for the joysticks?

That's good idea. Didn't even know about The Link before. Too bad preordering is over.

If you're in no rush, you could wait until they're available again in a few weeks/months. From what I understand this was a "test" run only, to see how many people wanted one, etc.

[EightBySix]

Hey - that looks perfect! It means I could go back to plan A and have a joystick in a drawer. Typical - just as I had decided to go ahead 

I'll press on with the centre panel and wait until he opens up for orders

[EightBySix]

So here are some contruction pics.

The offcut I'm using for the centre panel


Getting the edge straight - old school.


Plunge cut with the circular saw


Trimming to fit the monitor


At this point, I had to stop - before I could see it with the monitor. Good thing in hindsight, as the next job was cutting button holes, which I'm now gonna have in a drawer.

Back to sketchup for a bit now. Back in less than a year, hopefully.

[EightBySix]

After much fiddling, it fits. Nice and tight too. I'll put some turnbuckles underneath to make sure its secure though.

There will be a routed recess to hold the LED display, covered by a veneer sheet and then the glass. The veneer will also cover the silver bezel of the monitor.

Here is the way its going to work now. The joystick will lie flat and pull up with the action of the drawer.

I could also have the coin slot on the drawer surface, and use the drawer as the coin box. It has been bugging me where to put it without making a hole in the centre panel.
 

[Yvan256]

Here is the way its going to work now. The joystick will lie flat and pull up with the action of the drawer.

Can you elaborate a bit more on that joystick idea? You're not going to use The Link from Phreakmods?

[EightBySix]

Sure, it will fold in like this:


The mechanical action of the drawer opening will raise it up and down. In the up position, I'll have a microswitch to trigger the table opening actuator.

I love the concept of the PhreakMods link shaft, it made me realize that I could use the drawer concept after all. Then I realised that one of the main factors of the previous design was to make the table top as shallow as possible. With the new decor in the room, its no longer an issue - the furniture is 'chunkier' if that makes sense.
I watched a video of the stick and thought it wouldnt really work well with the kids and visitors. I can see me having to replace it often. Would be fantastic for some of the fold away bartops I've seen here though...

[Donkbaca]

I would ditch the coin box idea, I like using coins in coin doors, it adds a certain arcadey feeling, but its a pain to store the tokens.

THis might sound dumb, but where are you putting the PC and how are you running cables?

[EightBySix]

I would ditch the coin box idea, I like using coins in coin doors, it adds a certain arcadey feeling, but its a pain to store the tokens.

I'm going to use it as a money box - to fund future projects, and I kind of like the idea of making something to detect the coins. Phase II maybe 

THis might sound dumb, but where are you putting the PC and how are you running cables?

I have one of these:

Its about the size of a VHS cassette case, it's got a P166 in it, just about enough to run the classics.

As for wiring - with difficulty, especially since I'll have a linear actuator in there too. I think I have it figured out though. I'll post a pic of the internal layout later.

[surface tension]

Hey, this is coming on really well. Interesting to see all the ideas based around the control panel.

Great to see some more coffee table action... and in the UK!

[EightBySix]

Ok, so I know this is non standard, but I want the table to accept any coin, and give a credit for every 10p value inserted. So you could insert 1p + 2p + 2p + 5p and get 1 play, or 50p to get 5 plays, etc.
I'm going to use it as a kind of money box, or one of those places you keep loose change until there is enough to change into something bigger.

Here's how I've done it.

First, I took a chunk out of the side of a piece of wood:


Shaped it at an angle and put some slots in, to receive some brass contacts:


Cut and countersunk some lengths of brass. One for the coins to roll along, and several to go in the slots at various heights, to match the different coins.


Ended up with this:


Made a kind of wiring loom, so that I can detect when a circuit has been completed by the coin touching a brass contact. The contact then pushes the coin off the slope.


Here's a vid, to show how it works.

[drventure]

Nicely done! I like it

 

[Yvan256]

I sure hope those signals are debounced! 

What microcontroller are you using?

[Ond]

Nice woodworking, I like the LED idea also.