
<a href="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1294.JPG"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1294.JPG" width="400" height="294" alt="" title=""  /></a>



<a href="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1261.JPG"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1261.JPG" width="400" height="250" alt="" title=""  /></a>


<a href="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1268.JPG"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1268.JPG" width="400" height="250" alt="" title=""  /></a>


<a href="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1273.JPG"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/IMG_1273.JPG" width="400" height="250" alt="" title=""  /></a>

<h2>SCHEMATICS:</h2>
<hr>
<strong>Rungle MODS:</strong>
The architecture of the Benjolin starts out pretty simply, Two VCOs and one VCF. What makes the Benjolin a truly unique sound generator is the addition of a complex wave modulator called a Rungler. Here’s his explanation of what it is and a little on how it works.
“The purpose of the rungler is to create short stepped patterns of variable length and speed. One could categorize the circuit somewhere halfway between a plain S&H and a shiftregister-based pseudorandom generator. It needs two frequency sources to work and basically creates a complex interference pattern that can be fed back into the frequency parameters of the driving oscillators to create an unlimited amount of havoc. 

The rungler is basically a CMOS shift register clocked by one oscillator and receiving its data input from the other oscillator. The output bits of the shiftregister are used as a binary code 'to do something with'. E.g. in the Benjolin the last 3 stages of the shift register for a 3 bit code that is fed into a 3 bit DA converter. This DA eight level output voltage is fed back to the oscillator frequency control inputs. The output of the DA is the 'rungler CV signal'. To describe the rungler waveform in similar terms as like a sine wave or pulse wave I call it a 'stepped havoc wave'. “
For more info on the rungler and the benjolin in general go HERE.
CLOCK INPUT MOD:
In an effort to make the Benjolin completely modular I have added some buffering circuitry to allow external oscillators to control the two inputs to the rungler. The rungler requires waves with a bipolar swing, therefore I’ve included bipolar comparators at each of the two inputs, therefore nearly any clock fed in will be transformed into a bipolar +-9VDC square wave. 
BIT OUTPUT MOD:
The Rungler is a serial input shift register with a 3 bit output. The three outputs are fed into a DA converter and turned into a varying voltage. By adding output jacks at each output BEFORE it goes through the DA converter you have three gate signals which can be used as clocks, triggers or binary CV signals for other things. I’ve found them to be great drum triggers. 
The way shift registers work is that the state of each bit is passed from one to the next in order so it is helpful to position them in the correct order on your face plate. The order of operation is pin 2, 12, 3.
LOOP MOD:
In order for the Rungler to work it needs a serial data signal to be fed into the Rungler shift register  The serial data is generated by an XOR gate which combines oscillator 1 and the 3rd bit output of the shift register.
I found that the rungle sequence can be looped by changing the OSC input of the shift register. 
NO input = 8 step loop.
-9VDC input = 16 step loop.
External clock/16 step loop
In order to allow external clocks to be used, I added a bipolar comparator. The input to the comparator is pulled low, so if no signal is plugged in the output of the comparator will be -9VDC. That means that if no signal is plugged in and you send the comparator output to the XOR OSC input you will get a 16 step loop. This also means you can use a 3 position switch to select  OSC1 (random rungle signal)/ 8 step loop / 16 step loop (or external input). See the schematic below.






<a href="http://casperelectronics.com/images/finishedpieces/benjolin/BenjClockBuffer2.jpg"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/BenjClockBuffer2.jpg" width="400" height="250" alt="" title=""  /></a>

<hr>


<a href="http://casperelectronics.com/images/finishedpieces/benjolin/Benjolinmodularization.jpg"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/Benjolinmodularization.jpg" width="400" height="250" alt="" title=""  /></a>

<a href="http://casperelectronics.com/images/finishedpieces/benjolin/BenjAREnvGen2.jpg"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/BenjAREnvGen2.jpg" width="400" height="250" alt="" title=""  /></a>

<a href="http://casperelectronics.com/images/finishedpieces/benjolin/NewSchematic.jpg"><img src="http://casperelectronics.com/images/finishedpieces/benjolin/NewSchematic.jpg" width="400" height="775" alt="" title=""  /></a>

