Sunday, 18 November 2012

Sci Fi Siren Sound Tests

First tests of the Sci Fi Siren outlined in the previous post. The signal from the unit is a little hot so i've soldered a 68K resistor to the jack outlet from the negative to the ground to reduce it a little. I think I may up this to 200K if I take this unit out. I'm pretty pleased with the results. The LDR makes the unit quite unique, the low end bass wobbles are quite usable as well as the high squelchy sounds.

Friday, 2 November 2012

Modding a Sci Fi Sound Effects Kit

My inspiration at the National Media Museum Bradford

A slight return 

 The Smartkit1035 I used in this project is available from Quasar Electronics by clicking here.

The blurb on the instruction manual states "Any science fiction fan will enjoy this space age sound effects unit. Recreate those mysterious sounds from outer space with this fun project." At less than a tenner I thought it was worth a bash. Its been a long time since I've touched electronics but my aspirations remained the same. I wanted to build a DIY siren from a cheap kit and try to document it for others to peruse.

Step 1 building the kit

The kit was very easy to build using the instructions provided. I have been playing around with breadboards and wanted to play around with the resistors to find a nice hack that would extend the range of this little kit into a usable siren. To do this I soldered jump wires in place of the resistors on the PCB, as illustrated below.

Jumper wires will be fed into a breadboard to experiment with different pots and resistors.
Note the speaker is soldered to the board during testing. 
A more detailed view of the board. Note the absence of the IC CD4001 at this stage.

Step 2 experimenting with components

Jumper wires attached to the breadboard with resistors and an LDR in place

I played around with various different components by connecting the jumper wires to the breadboard and connecting components between them. After several hours of fiddling I came up with the following components to to add to the PCB board and finish off the mod:

R1: 4.7K
R2: Light Dependant Resistor
R3: 6.8K
R4: 3.3K
R5: 100K Linear Pot
P1: 100K Linear Pot
Momentary push button - breaking the ground line from the battery clip

Breadboard with different triggers, LEDs and pots being tested.
The mighty test rig!

 Step 3 installing the remaining components

I became very friendly with my solder sucker during this stage, making sure that I did not damage the copper traces on the PCB board. If in doubt, use your iron really gently to heat the solder on the board and get the sucker nice and close. Be sure not to keep your iron on the board too long as this may damage the trace.

Completed board. Note the speaker output has been replaced by a jack input.I used electricians tape to tidy wires together and provide insulation where the jumper wires meet the wires from the battery clip
A close up of the board.

Step 4 designing the enclosure

This is the part I have struggled with in the past. I've spent some time watching Youtube videos on the subject and have invested in an HSS stepped drill bit, similar to this. I mused with the type of material I should use for my enclosure. Sure, ABS plastic cases are easy to work with, and cigar boxes from Ebay look great, but I wanted something more rugged for this unit. I settled on using a diecast aluminium enclosure (size 1590bb) from TheFuzzShack.

Once my enclosure had been delivered, I measured the interior and exterior dimensons and drew up plans of how the components would sit inside, and where the drill holes would be placed. I found it best not to rush this step, and try various different solutions to see what would fit best. Some of my sketches are included below.

Concept sketches for the case design and layout.
 Once I was satisfied with my design, I drew up a template on paper and placed it over the top of the enclosure to make sure it would fit.

Enclosure with design overlay. 

As I am going to build my siren with the screw-on plate as an access to the battery on the underside of the unit, I then trimmed down my paper template, placed it on the inside of the enclosure, and drilled pilot holes using an old upright drill I acquired last year as illustrated to the left.

I then drilled out the holes using my stepped drill bit to the required diameter for each component. The holes were easy to drill with my new bit, even the 30mm hole for the trigger button. All that remained was a little filing to remove any sharp edges.

Step 5 insulating the enclosure 

 I knew from speaking with others that the circuit my short if the metal components touched the aluminium exterior. Using my paper template again I cut out a piece of 2mm thick fibre-board and drilled holes in the correct position. I then used a glue gun to mount the LDR in place.

The paper layouts I used in this project
On testing it became obvious that the unit was still shorting. To remedy this I used the paper template again to cut out an over-sized piece of felt that would sit between the enclosure and the fibre-board. I then cut holes out of the felt for the pots and switches to poke through and held on place using magic tape.

Step 6 putting it all together and testing

Once I had everything ironed out, it was simply a case of screwing everything together and testing the unit. I took my time with this project over the space of a week, trying not to do too many steps at once and sleep on any major decisions.

I have some ideas for a case design but I'll leave that one for another post. In the mean time I need to plug this thing up to a delay line and see what I can do.... but its sounding good. I'll put some sound clips

Inside the finished unit. Note the fibre-board and felt lining.
Note the glue holding the LDR to the fibre-board
The finished unit

Tuesday, 12 April 2011

Analogue Delay

Another slightly off-topic post this evening. I have recieved in the post today a Behringer VM1 Vintage Time Machine. Essentially its an analogue delay unit similar to the Electroharmonix Memory Man.

I was put off buying Behringer gear a few years ago after a rather nasty encounter with one of their mixing desks. After stumbling across the VM1 online a few weeks ago I was willing to give them another try, partly due to the price of the unit, and partly due to what it will offer. I doubt I could build a clone for much less money.

The package comes complete with a DC power supply and full instruction manual. The unit itself is larger than I first assumed and appears to be very well built with all components seemingly high quality. LEDs are included for power and overload - a useful addition.

I plugged the unit directly into my mixing desk on an AUX and immediately got to work testing this delight. I'm really pleased with how it sounds. Totally different from my trusty Ibanez DD1000, the VM1 has a very warm tone which degrades beautifully when the delay kicks in. Increasing the feedback and varying the delay time creates some rather tasty self ocillations. First impressions are generally good, i've noticed it can sound a little muddy, but i'm yet to play around with sweeping my EQ and feeding back sound on sound delay. I'm really looking forward to putting this to task in future dubs.

If you are after a cheap introduction to analogue delay I recommend this unit highly. It may lack the finesse of a vintage machine, but it clearly has found a nice home in my attic studio.

I'll upload some sound clips asap to give you the feel of the unit. More posts to come in the next few weeks as i've started building and documenting a vero board dub siren.

Friday, 4 February 2011

Rebirth - Sound Experiments

First musings taking samples from the MPC Percussion Synth outlined in November, pictures to follow. Samples are sequenced in FL Studio and the mix is raw. More to follow.

Rebirth (Dubstep Mix) First Mix by isistowersmusic


Sunday, 30 January 2011

Cheap Dub Siren Part 3

Been puting my cheap and cheerful siren to the test tonight. See the sample below. With a little tape delay it sounds quite splendid and the extra control using a push to make switch makes the unit rather playable.

I'm pretty happy with overall build of the unit and have learned a lot from my experiences customising the enclosure. On reflection, fitting the unit into a small space requires a lot of preplanning, preparation and thought. I'll put down some words on this another time, in the mean time however ... Junior Delgado in fine voice.

Dub siren jnr delgado by isistowersmusic

Building a Cheap Dub Siren Part 2

This is my first enclosure design. I'd had a couple of attenpts over the years which generally ended in sadness. I spent a long time looking at the guts of the siren next to the empty enclosure. The tricky thing was making sure the battery and jack socket had room to breathe.

Step 1: Screw in knobs and buttons and solder connecting leads to the board.

 Solder the cables from the  pots, switches and triggers to the board. I've stengthened the join in places with wire and extra solder. Not so neat but very effective.

Tone pots, switches and trigger mounted (from the inside) I had to countersink the drill holes to push enough of the component through to attach the mounting nut.

Step 2: Trim excess from tone pot control with hacksaw and attach control knobs