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Category Archives: Just for fun

Sound reactive LEDs

Posted on 3.11.2013 by Vesku Posted in Just for fun, Utility .

I’ve spent a lot of time inspecting how could I build up a system, which blinks LED lights in time with sound. Found some plans from the internet, but they all sucked. At first I tried to use a TIP31 -transistor, which in fact works somehow, but needs a lot of a amplification to work. My bass amp’s effect loop’s send’s signal wasn’t strong enough to blink the light. Added MXR’s Microamp to the line, and it worked just barely.  TIp31 needs  at least 0.7 V to conduct, which you don’t have in most cases. So, f**k the TIP31.

Instead, one good solution is a LM358, which is a low power dual operational amplifier. It can be used to amplify the DC signal generated by a microphone and act as a LED driver. It has DC voltage gain of 100db, and runs with DC-power from 3 volts to 32 volts. The circuit is as following:

 

sound_reactive_leds

I usually hate circuits containing connections between two sequential rows in vero board, but this time I tried to squeeze the circuit as small as possible. The driving signal can be almost anything. Signal from microphone, instrument level signal from guitar…
It’s very sensitive, so instead of amplifying the signal even more, we have to brake it down instead. The sensitivity can be adjusted with the value of R1 -resistor in the circuit. To make it easily adjustable, use appropriate potentiometer in place of the resistor. Something like 5K pot is worth to try. Everything below 1K makes the leds crazy even if you breath too loud.

R2 -resistor is for limiting the current going to the LED’s. If you plan to use several leds in your circuit, you can use a jumper instead, and connect appropriate resistors in led rows. How many led lights you can use in series depends on the input voltage used, and the colour of the leds. Blue and white are the brightest, and with 9 volts current you can run only 2 or 3 in series. It’s up to to the forward voltage of the led light, which is around 3 volts with white and blue. But that’s not a problem, just create several parallel led stripes.

In the video below I’ve built this system inside a 1590B -box. The LED stripes are built into mini sized guitar. I removed the pickup, and assembled the LED stripes into small piece of wood which I installed into humbucker frame. My bass amp’s direct out is used for the operating signal. So, basically it’s just instrument level signal, and 5K resistor pot is used for adjusting the sensitivity. This is our band’s on-stage decoration, and it takes its signal from the bass drum.

 

 

 

1 Comment .
Tags: Decoration, Just for fun .

Pimp your pedalboard

Posted on 25.10.2013 by Vesku Posted in Decorations, Just for fun .

A good sturdy pedalboard and the power block can be mind bogglingly expensive considering the price of the raw materials. It’s very easy to build your own and, in pursuance, add some decoration to it. If I can, you can.

At first, spend some time planning the size and form. Personally I use Autocad with every project as I’ve noticed that drilling and sawing without planning and measuring carefully first becomes quite expensive in the long run. This is my plan done with Autocad:

 

pedalboard_piirustuws

 

Bought the materials from the local lumber trade with some 6 euros. The price included the sawing job for the plywood board.  Took 15 minutes to glue and screw it all together. Personally I dislike commercial powerblocks as they are bulky and expensive for no reason. All I need is an efficient power source with daisy chained cable. The problem with the daisy chain cable is that the branches are always either too long or too short. There is too many of them, or too few. As a result you have power cables crossing here and there. So why not to put separate power jacks into board, and then solder single power cables with appropriate lenght? Like this:

 

pedalboard_virtajakit

 

Eight power feeding jacks can power up more pedals this board can take.

Then the decoration. You know this back and forth moving light from the TV series Knight rider? Got the original idea from Paul in the lab, and developed it a bit more. I added one more 555 -timer chip to create a sequence instead of non-stopping motion. The 555 timer IC is very interesting piece of tech. When used as a astable timer it works basically like this:

 

275px-555_Astable_Diagram.svg

The up and down time are depending on the R1 , R2 and C -values, and the total lenght of the sequence is depending on the C-value. Uptime can be calculated with following equation:

Uptime = ln(2)*(R1+R2)*C

Downtime from each pulse is equated like this:

Downtime = ln(2)*R2*C

Don’t mind the tech talk, but use some online calculator to get the result you want. In my case I needed 3,6s of uptime and as long frequency as possible. 3,6s is time which the circuit needs to go back and forth once. Then it takes 3 seconds break and starts again. The only limitation is that the duty cycle can never be less than 50% in this circuit. All this collected together the circuit looks like this assembled into vero board:

Knight rider

Feel free to use it for your needs. The correct values are R1=5,6Kohm, R2=47Kohm and C=100uF. If you want you can use a switch which selects if the circuit is working continuously, or by the sequence. ”+9V” is for the sequential operation, ”Vin” for continuous. All the diodes are 1N4148. Notify the double link below the CD4017. Assembled in the pedal board with blue leds looks nice. Too bad I don’t have a video. I added a switch to turn the whole circuit off when needed. If you do the same, just cut either the ground or the current wire with appropriate switch to do this.

 

pedalboard_knightrider

 

Some glowing light still to add. Used 5mm ultrabright leds in both sides of the board:

 

pedalboard_valot

 

Powering up the leds is something to talk about. LED diodes always need a resistor when used with 9V voltage. Otherwise they will be dead immediatelly when connected. The correct value depends on the color and the amount of the leds. I think blue and white are the only ones bright enough for use.  The forward voltage for both the blue and white led is around three volts. Try three leds in series, and if all the leds light up, then leave like it this. If not, use two leds in series, and the third one parallel.

The resistor values are something like 150 ohms for the leds in series, and 300 ohms for the single one. White led is usually a bit brighter than the blue one, so experiment. In any case, the result is a eye burning floodlight, so do not stare straight to it. It still safe because it’s directed towards the floor.

I assembled the led strips to the rail meant for hiding cables:

 

pedalboard_valot2

 

Only competition stripe to add. electrical tape is good for this:

 

Pedalboard

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