| WAH | FUZZ | SWITCHING | SUSTAIN | ATTACK/DECAY | VIBRATO/TREMOLO |
Introduction
The two modules may be used in series with the input to the Fuzz module followed by the Wah otherwise the wah would be ineffective.The wiring arrangement provide for four mode of operation as follows:
1 Wah 2 Fuzz 3 Fuzz-- Wah Foot By-Pass
Figure A shows the external wiring for each modules (for identification chose your own wiring colours )
Figure B details the basic power supply wiring. ( See "E" for option )
Figure C Shows the combined wiring of the by-pass switch S4 with the rotary switch mode selection S3. In order to indicate that the by-pass is active a small optional circuit is added , a green LED is indicated ,Q1 can be any high gain PNP small signal transistor , S4 as wired is said to be a true by-pass circuit. Two 100K resistors can be connected to the input and output of S4 to ground to help eliminate the POP from the amplifier when S4 is activated.
Figure D show the wiring details of Rotary switch S3 , position # 1 =Wah , #2 = Fuzz, #3 = Fuzz-Wah. S4 can be activated at anytime to override any of the selected mode.
Figure E Shows an optional circuit to use a wall plug transformer input . Wall plug units have the center pin positive or negative , the circuit uses a protective steering diode bridge , regardless of the polarity input the output of the bridge will always be positive. A 9V regulator is used with a 470uf filter capacitor . The output of the regulator is connected as shown to a SPST switch. A 9V battery can also be used at the same time two diode in series are used to block the higher voltage potential of the regulator to the battery incase the regulator may be lower than 9V otherwise one diode would be sufficient to maintain a half volt lower potential.
In order for the voltage regulator to be effective a wall supply unit rated at 12 volts minimum and 100 mA is required since the total current consumption of the unit including the LEDs should not exceed 20mA and a small regulator in the TO92 package is sufficient. More information can be found here on regulators .An alternative to the diodes in the battry circuit is to connect the battery to a 2 wires closed contact input jack of the type required by the wall unit output connector. In this case eliminate the diodes and connect the jack battery output directly to the switch.
Input or Input and Output Jack connections
Below is the wiring to illustrate how an input or the output jack can be used for both the signal input and power supply connection instead of using a seperate power on/off switch . As the plug is inserted the negative side of the power supply connection is made with the plug body and the open connector contact while the signal is made with the insulated connector tip of the plug with its own lug .
The second illustration shows the input and output jacks connected in series make or break the negative supply connection . This is the safest way to protect the battery supply .
When using the Wah module without the wah action the signal is passed through but with a small loss of the higher frequencies which might not be objectionable to you. In that case to simplify construction and saving you may well decide not to install a by-pass switch. If you desire to install the by-pass switch , connection layout is shown below.
Electronic by-pass switch
The last drawings show how you can use IC's to make and electronic true by-pass switch . A DPDT ( Double poles double throw ) foot switch cost anywhere from $ 12.00 to $ 17.00 ( canadian $ ) and the price is still going up . You can save up to 2/3 the cost by making your own with simple IC's using a CD4016 or CD4066 and one gate of a CD4049 for one design or CD4053 and a few resistors for the other design switch .
The only draw back is that the power supply must on to activate the switch. A simple SPST push button switch can be used , a heavy duty one can be had from most electrical supply stores.Using CMOS 4016 or 4066
Both chips are pins compatible and contain four SPST switches . We use all four switches in a flip-flop fashion using one gate of the 4049 to invert the switch signal to two of the switches to obtain a DPDT action as shown .
When the power is on and the foot switch is open the CD4016/66 switches c-b and e-f are held closed by the 10K resistance connected to ground allowing for the by-pass position . As soon as the foot switch is closed + 9 volts is applied to pins 12 and 13 of the CD4016/66 and pin 3 of the CD4049 and overcome the grounded gates and allows a-c and d-f to close and insert the circuit between a and d .
A suggested IC layout is shown and a representation of a similar DPDT switch action is shown with the pin connections . Gates resistance is very low on both designs and does not affect the signal level , I have tested them after assembly and was very satified with the operation .
4016/4066 IC Layout and PCB shown
Using the CMOS 4053
Below is a DPDT switch using a 4053 IC , the on board chip contains three SP2P ( Single pole two positions) and we use two for the circuit switching and the third one to activate an LED/ON indicator.The trigger level requires a positive high of about 4.5 V and will respond well with + 9 v from the switch through the 200 ohms resistance used as a safety current limit to the gates of pins 9 , 10 and 11 connected together which are held to ground with one 100K resistance when the switch is open .
As the CMOS are highly sensitive to noise , we must ensure that any outputs are not left floating and we use 100K ohms load resistances from all outputs to ground when the switches are off . A small 2uF capacitor should be used as shown at the input and output from the jacks .
To minimize the current flow throught the switch to the LED , a resistance from 1K to 3K used as a current limit for the LED and is connected from pin 14 to the + 9v and allows adequate brigthness .
4053 IC Layout and PCB shown twice the actual size
Using a Push Button
Its is possible to use a push button or a microswitch with normally open position to activate a flip/flop which will change the ON/OFF state of the 4053 . A Flip/Flop is made with a CMOS 4011 as shown below .
When the switch is closed the positive voltage charges the .1uF capacitor from the 100k resistor and produces a positive output at gate C pin 4 which triggers ON the inputs pins 9,10 and 11 of the 4053 . The capacitor remains charged and maintains that state until the next closure of the switch allows the capacitor to discharge throught the 100K resistance allowing gate C pin4 to change state and trigger OFF the 4053 .
4011/4053 Layout and PCB shown actual size
Using a push button with a relay for a true by-pass switch You can use voltage up to 14 Volts BUT the current must never exceed 100Ma with the transistor shown , but a larger transistor can be used .
The PCB of your choice can be included on your main circuit board and connections made with either tracing or wired from point to point .
Next page Sequential Electronic Switching
I hope you have enjoyed studying this project , if you have any questions please feel free to contact me .
| WAH | FUZZ | SWITCHING | SUSTAIN | ATTACK/DECAY | VIBRATO/TREMOLO |
