A door bell with multiple samples and a turntable you can actually scratch on!

So, a couple of years back following a Facebook post about an idea for a doorbell with separate rings for each person in my house, my mate threw in the idea for it to include a turntable you could scratch on. Being the kinda guy that can't say no to a challenge....that's what (eventually) happened!

This project is a bit of a hack but cost me nothing, and I made it entirely from stuff I had kicking about. However, I do have a rather ridiculous amount of stuff kicking about. You should be able to source all the bits from boot sales/Freecycle/eBay for very little. Things I used included....

Ancient laptop (a clevererer person than I may be able to do this with a r-pi)
Old USB mouse & keyboard
Mechano from my folks loft
12mm Ply
Computer speakers I spotted in a skip
Buttons from an old fruit machine
A lever arm micro-switch
Little rubber wheel
Waterproofing paint
7" record
Scrap of perspex
Wire
Glue

Hope you enjoy the instructable and please comment if you try something similar or have any ideas on how you would have done it.

Step 1: Plan

As per usual not much planning going on here...just quick sketch on AutoCAD and a failed first attempt.

This is my second DJ doorbell. Mk1 was pretty badly made and the British weather killed it within a couple of months. Mk2 was designed with durability & weather proofing in mind, and with three separate rings for each of the people living in my house as opposed to just one. It's survived a pretty harsh winter, and so far I'm pretty happy with it.

A lot of this project was worked out on the fly using whatever I had to hand, so after figuring out a basic layout in AutoCAD I took to the shed and got to work!

Step 2: Make the Box

Luckily I'm a carpenter so had a lot of tools available to me. If you don't have access to a plethora of tools, make friends with someone that does, or modify your design to work around what you've got.

First up I cut some 12mm ply on the table saw into strips 180mm wide (front and back), and 70mm wide (edges). I also cut a little bit 18mm ply into a 100mm wide strip (hat)

I marked a center line on the front piece, and with my mitre saw set to 22.5 degrees I cut the front & rear panel to a point.

Using a square/compass/ruler, I marked out where my buttons/speaker/turntable would sit, and used this set out the base line. This square cut was made on the mitre saw.

Next I put a 6mm rebate bit in my router, and cut a rabbet into the inside edges of the front and rear panel, and along the long edges of my 70mm wide side pieces.

The side pieces were then cut to size, and more rabbets cut for joints on the bottom. I set my mitre saw at a tilt of 22.5 degrees for the appropriate joints at the top of the box.

Using hole cutters I cut the holes for the speaker/buttons/turntable axle. A slot for the "crossfader" micro-switch lever arm was hacked out with chisel.

The box was then assembled using Gorilla wood glue, clamps, and pins.

Step 3: Turntable Mechanism

This is a bit of a hack, but in Virtual DJ (free software) you can scratch a virtual turntable using the jog wheel on a mouse. So, all I had to do was get a little turntable geared onto a mouse wheel.

Some Mechano recently surfaced from my parents loft, and this is what I used to build a frame for the turntable.

I had a little rubber caster wheel, and this would transfer the axle rotation onto the mouse wheel. I super-glued a Mechano wheel and washer to the rubber wheel, and built a frame around it which slotted nicely into the box and screwed in place.

A bit more Mechano screwed on the back of a USB mouse and I had a pivoting arm, that with the help from a little spring, would hold the mouse wheel tight against the rubber wheel.

It's kind of hard to explain....just look at the pictures!

Once I'd checked it was working I took out the frame, and gave the box a few coats of waterproofing paint.

Step 4: Keyboard Hack

To trigger things in Virtual DJ you can map keys on a keyboard to perform actions such as samples or crossfader position.

I had an old USB keyboard that I took apart and lifted the circuit board from. On most keyboard circuits you have a series of 20 or so pads, and I poked these with a bit of wire (while plugged into computer) until I knew which combination of pads would send useable key presses. If you can find key presses that work off a common base it'll reduce the amount of wires that will need to run from the box outside to the keyboard circuit inside.

I soldered wire to the pads, which would run to the buttons and crossfader micro-switch in the box.

Step 5: Speaker, Buttons, Crossfader, and Wiring

My speakers that were liberated from a skip had a primary speaker that was powered, and a slave speaker that ran off the primary. The slave speaker would be the one in the box, so I took it apart and stripped out the driver. This was installed in the inside of the box with screws.

My buttons were ex-fruit machine buttons I had left over from a different project. I put my own labels into the buttons, and they screwed into place. I didn't have any of the proper bulbs so just wedged in some white LED's.

Now for the wiring....For the LED's I daisy chained all the positive and ground terminals, and this would have a 3V supply so no resistors were needed.

The buttons and crossfader micro-switches all had a common terminal, and an individual terminal. Since it was basically making a short between different pads on the keyboard circuit again no resistors or fancy electronics were needed.

I'm a bit of a noob with electronics, but have attempted a cheeky circuit diagram (see pic)

Step 6: Record

Having a decades worth of vinyl which was now redundant thanks to the digital DJ revolution, I picked out a classic 45 from my stash....Lipps inc. - Funky town.

After a quick check to make sure it wasn't rare or valuable I trimmed it down a bit using a 152mm hole cutter. I then bolted a Mechano wheel onto it so it could be fixed to the turntable axle.

I didn't want the record rubbing against the sticky waterproofing paint, so I whipped up a "scratch plate" from some 3mm perpex using hole cutters, and screwed it to the box.

Step 7: Virtual DJ

I had an old laptop that had been sitting about for like 5yrs, so I gave it a clean wipe and a fresh install of windows. It still took forever to boot or launch anything, but it had enough oompf to run an old version of Virtual DJ. Sorry for photos instead of screenshots....but that's how frustratingly slow it was!

I downloaded an old version of Virtual DJ that is free for home use from here.

My housemates & I picked out the songs we wanted for our rings, and I edited them down to around a 10 second clip in Logic. These were loaded into the sampler section in virtual DJ.

I also edited a few scratch samples (ahhh...fresh...aw yeah) into a little clip and this got loaded onto a turntable in Virtual DJ, and set to loop. You can either have the virtual turntable playing and have your mouse wheel acting as a jog wheel, or leave it and have your mouse wheel control the rotation directly (I opted for the second).

Then is was simply a case mapping the key presses from the keyboard circuit board so the buttons would trigger the 3 separate clips, and the crossfader micro-switch to click the virtual crossfader on. A video on how to do this can be seen here.

Step 8: Put It Up

I had a total of 9 wires and a USB that would need to run from the box outside to speaker/keyboard circuit/computer inside (about 2m away). I used a length from a broken ethernet cable (8-core), and a bit of speaker wire (2-core).

Before putting the back on I tested everything was working. I fed a bit of plastic pipe through though the back panel and sealed it in place in the hope that this would be enough to keep the box sealed & waterproof. I screwed the back panel on and gave it a few coats of waterproofing paint. (I'll probably have to fix it one day so didn't want to glue)

Luckily I had an old broken light on the outside of the house that already had wires running through the wall, so I just had to remove it and widen the existing hole for my wires using a 16mm masonry bit.

Then it was a case of feeding the wires through the wall, and fixing the box to the wall. I gave it a little hat using the 18mm ply from step 3...fingers crossed that's enough to protect it!

I removed the battery from the laptop and set it to never go to sleep (even if the lid was closed), set up the software, boxed it onto the wall inside, plugged everything in.....and Bob's yer Dad's uncle!

Step 9: Finished!

And there you have it!

A lot of this project was sort of hacked together, so please leave comments on how you would have done it, alternative methods, and generally useful things that will help out anyone having a crack at something like this.

Please comment and share with me any questions you may have, and if you're giving it a go.

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