Modifications

Modifications and diagrams by: Harry Goodwin

Wiring layout of Boris's circuit board

1999 version

 

Split Power Supply

This board is designed to be powered by an external 12 volt DC power supply. In the building phase, variable resistors were used on pin 3 (marked Adj) to achieve  proper voltages, 3v, 6v. Refer to the LM317 spec sheet below. They  were then replaced with fixed resistors (for reliability) of the proper values, 390 ohm and 1k ohm. If for instance you wanted to use a 9 volt dc power supply you would  need to change the values of these resisters. If you were to use a 6 volt DC power supply, then you would only need  a 1 regulator circuit for the 3 volt supply. Large heat sink(s)  are recommended, as the regulators do get warm.

Any external power supply you choose should be rated at least 1 amp.  If you are to run more than one Boris from a single external  DC power supply then a higher rating is recommended. figure on 1 amp per Boris for best operation.

This board is small enough to be mounted on top of the battery compartment lid inside Boris's head. My brother used a hot glue gun to secure it, he then mounted a coaxial DC input jack to the back of the skull.

He modified 3 Boris's last year and ran them from a single 12 volt regulated DC power supply rated at 3.5 amps for three weeks ( about 6 hours per night) without any problem.


Microphone to Line in

Step 1
This modification is rather simple. (inset above) Open up Boris's head, carefully  remove the black plate, via the 4 screws, trace the microphone wires to the board.Unsolder the  (white lead, old Boris, 1999) (red lead, new Boris, 2000)  Place a 100 mfd electrolytic capacitor inline, solder the (+) lead to the board, where the mic wire had just been removed, and the (-) lead to the mic wire.  Be sure your solder job, or the bare leads of  the cap do not come in contact with any other part of the circuitry. Reassemble Boris.
The importance of the capacitor
Boris uses an electret microphone which means there's DC voltage present across the mic.
The purpose of the capacitor is to block the DC from going into your audio equipment.

Step 2
Cut the wire towards the mic end, leaving several inches, in case you ever want to re-attach it. Strip
the wires about 1/2 inch or so, solder them to an 1/8 inch phone plug. Connect the line side (the insulated wire) to the inner
lug. Connect the shield, (bare wire) to the outer lug. Now just plug Boris into any headphone jack, your portable tape
player, Boom box, or the line out of  your computer's sound card.

If  Boris Sounds distorted;

1: Boris's input is probably being over driven, turn down the volume of your tape player, or volume control in your
sound card software.

2: Change Boris's voice changer switch to the number 4 position, "Amplify" for best clarity.
You can make much better voices using sound editors such as Cool Edit or Sound Forge.

3: Weak batteries, or insufficient power supply.

Hooking Boris to your stereo would require a different type of plug, an RCA phono plug.  If your Boris is already wired
with a phone plug, you can make or buy an adapter, or you can install an RCA phono jack to the back of Boris's head.
This way you could use the standard audio patch cord to plug boris to your stereo's "Line out" or "Tape out" jacks. These
output levels never change regardless of volume settings, so you may want use a stereo mike/line mixer to adjust output.
you never want to hook him up to your speaker outputs as damage can result. Remember Boris was designed for small
input signals from a microphone, So pumping 60 watts into him could result in a boris barbecue.

LM317  Spec Sheet


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