Title:
ELECTRIC GUITAR SYSTEM
United States Patent 3813473


Abstract:
An electric guitar having a plurality of strings and including circuitry for adjustably attenuating the input signals from the strings not played, circuitry for adjustably varying the attack of the output signals representing notes and chords, gain control circuitry utilizing a photoconductor, and a mechanically coupled feedback path for applying output signals back to the strings to sustain vibrations.



Inventors:
TERYMENKO P
Application Number:
05/301372
Publication Date:
05/28/1974
Filing Date:
10/27/1972
Assignee:
INVESTMENTS LTD,CA
Primary Class:
Other Classes:
84/702, 84/711, 984/367, 984/374
International Classes:
G10H3/18; G10H3/24; (IPC1-7): G10H3/00
Field of Search:
84/1
View Patent Images:



Foreign References:
FR673375A
Primary Examiner:
Wilkinson, Richard B.
Assistant Examiner:
Weldon U.
Attorney, Agent or Firm:
Davis, Hoxie, Faithfull & Hapgood
Claims:
I claim

1. An electronic plural-stringed musical instrument having:

2. The instrument of claim 1 wherein the means for selecting includes

3. The instrument of claim 2 wherein the degree of attenuation is adjustable.

4. An electronic musical instrument having:

5. The instrument of claim 4 wherein the motion producing means includes an electromagnetic coil and core assembly and a substantially rigid connection between the assembly and the bridge.

6. An electronic plural-stringed musical instrument having:

7. The instrument of claim 6 wherein the means for selecting includes diode means having a threshold voltage at the threshold level.

Description:
The present invention is a musical instrument comprising a guitar body having several novel features and associated electronic circuitry.

Current electric guitars, and the devices for modification of their output signals commonly known as "fuzz" boxes, have several inherent limitations in performance because of certain aspects of their design. While these limitations do not affect the utility of such guitars and devices for many musical purposes, they do prevent the achievement of desirable musical effects.

For example, with current electric guitars it is difficult to produce a sustained note, that is, a note which will not "die down", except by utilizing an extremely high sound volume level. Therefore, a musician must play the guitar very loudly if he desires to use the sustained-note effect. Furthermore, because the sustained-note effect in current electric guitars is dependent on the total acoustical environment of the guitar, it is difficult to predict which notes will sustain themselves in a given setting. This means that a travelling performer has no assurance that a note which will sustain itself in one concert setting will also do so in another.

Current electric guitars severely limit the ability of the performer to play melodies or chords without accompanying interference from the strings not played. Sympathetic vibrations among the strings cause signals to be generated at strings other than those being played, and these spurious signals are amplified and (when the guitar is used in conjunction with a tone modification device) modified along with the desired sounds, producing interfering output signals and, in the latter case, inter-modulation distortion. In fact, it is difficult just to keep conventional guitars silent, especially when they are used in conjunction with tone modification devices.

A third limitation of current electric guitars derives from the fact that the action of a guitar pick on the string makes the guitar in a sense a percussive instrument. This limitation is accentuated by the use of "fuzz" boxes and the like. Flowing melodies are difficult to execute, and the louder the instrument is played, the more prominent is the initial click of sound produced by the plucking of the string.

The present invention overcomes each of these limitations of current electric guitars and thereby allows a performer greater opportunity for display of his ability. A sustained-note effect, reproducible in any acoustical environment independent of the performer's volume level, is achieved according to the invention by utilizing a mechanically-coupled feedback path within the guitar of which the string is the frequency-determining factor. The undesirable effects of sympathetic vibration are eliminated by providing performer-controlled, automatic selector circuitry to eliminate unwanted signals from the strings not played. The percussive feature presently inherent in electric guitars is controlled by other performer-controlled, automatic circuitry which gives the melody or chord a bowed rather than struck sound.

These and other features of the invention will be more apparent from the illustrative embodiment described and illustrated in the accompanying drawings, in which:

FIG. 1 is a block diagram of the guitar system of the present invention, as applied to a six-string guitar;

FIG. 2 is a circuit diagram of the Automatic Input Selector stage;

FIG. 3 is a circuit diagram of the Voice Module stage;

FIG. 4 is a circuit diagram of the Mixer stage, also showing the Preset and Stepping Voice Selectors and, in schematic form, the Expression Pedal;

FIG. 5 is a circuit diagram of the AGC and Percussion Regulator stages, also showing, in schematic form, the Volume Pedal;

FIG. 6 is a circuit diagram of the electrical portion of the Sustain Vibration system;

FIG. 7 is a cut-away side view of a guitar body containing the mechanical portion of the Sustain Vibration system; and

FIG. 8 is a top view of the guitar body shown in FIG. 6.

Referring first to FIG. 1, this Figure at its left side shows signal inputs from individual pick-ups mounted beneath each of the six guitar strings A, B, C, D, E and F, which, in the present invention may be made of any ferromagnetic material. The signal from a given string will be hereinafter referred to as, e.g., signal A, signal B, etc. Signal A enters the Automatic Input Selector circuitry associated with string A and, if no "ATTENUATE" or blocking signal also enters that Automatic Input Selector circuit, signal A in amplified form is applied to the input of the Voice Module circuitry associated with string A. In the Voice Module, the signal from string A is processed to produce, in this illustrative embodiment, six "voices" or electronically modified and amplified versions of the original signal. These voices are identified herein by one of the subscripts u-z following the letter of the string from which the signal is derived, as for example, Au, Av, Aw, Ax, Ay, and Az. At the Mixer all of the like voices from the several strings are combined into a single voice, e.g., Au, Bu, Cu, Du, Eu, and Fu are combined into a single voice hereinafter referred to as voice U. Similarly, all the individual v voices are combined to produce voice V, etc.

Referring now in detail to FIG. 2, the circuitry of which it should be understood is repeated for each string, signal A from the magnetic pick-up mounted in the guitar body beneath string A is applied to the base of transistor Q1 across the parallel arrangement of potentiometer R1, used to balance the amplitudes of the incoming signals from the various strings, and C1, which shunts any radio frequency noise to ground, and through coupling capacitor C2. Signal A is also applied to the base of transistor Q3 through coupling capacitor C3.

The function of the Automatic Input Selector (AIS) circuitry shown in FIG. 2 is to provide the performer with the means to attenuate or completely block all signals from the strings not being played at a given time, thereby eliminating unwanted sounds from the melody being played.

Transistor Q1 amplifies the signal, which then passes through capacitor C4 to diode D1. Potentiometer R2 is adjusted to allow only a short burst of negative-going signal to pass diode D1, which in this illustrative embodiment may have a threshold voltage of about 0.3 volts. The spike of signal passed through diode D1 passes through coupling capacitor C5 to transistor Q2, which is biased into saturation when no signal is applied. The application of the pulse to the base of Q2 results in a strong positive-going burst of signal at the collector. This pulse is applied across diodes D100-04 to the "ATTENUATE" inputs of the AIS circuitry of the other strings, not shown. For example, if the AIS circuitry for string A is being discussed, then diodes D100-04 would be connected to the "ATTENUATE" circuitry associated with strings B, C, D, E and F.

Direct coupled transistors Q3 and Q4 and their associated resistors comprise a flat response circuit capable of amplifying or attenuating the signal applied at the base of Q3 depending on the bias conditions. The bias conditions in turn are dependent on the state of transistor Q8, connected between the positive source and the collectors of Q3 and Q4. The AIS control is exerted at this point, by causing Q8 to vary between cut-off (in which case the supply voltage to Q3 and Q4 is low and the output at the collector of Q4 is attenuated) and saturation (in which case the supply voltage to Q3 and Q4 is relatively high and the Q3-Q4 combination functions as an amplifier).

The AIS circuitry attenuates a signal in the following way. If string B only is struck, in the manner described above a positive signal pulse appears at the "ATTENUATE" input of the AIS circuitry of string A and is applied to the base of transistor Q5, through potentiometer R3, which functions as a sensitivity adjustment. Transistors Q5 and Q6 are arranged in flip-flop fashion, so that the "ATTENUATE" pulse just described puts Q5 into saturation and Q6 into cut-off. Had string A been plucked, Q6 would have been put into saturation by the application of the positive burst to the base of Q6 through diode D2. With Q6 in cut-off, its high collector voltage is applied to the base of transistor Q7 across photoconductor PH1, a variable resistor located in the AIS pedal, operation of which is controlled by the performer.

The AIS Pedal, and other performer-controlled pedals discussed below, all include a neon bulb and one or more photoconductors. Depression of the pedal by the performer varies the exposure of the photoconductor to the neon bulb NE1 and hence the characteristics of the circuit of which it is an element. In the present case, if PH1 is at its lowest resistance value (pedal fully depressed), the voltage applied to the base Q7 puts that transistor into saturation. This in turn lowers the collector voltage of Q7, which lowers the base voltage of transistor Q8, biasing Q8 out of saturation and sharply reducing the supply voltage to transistors Q3 and Q4. In this way, the application of an "ATTENUATE" signal to the AIS circuitry of a given string, given the depression by the performer of the AIS Pedal, causes the output from transistor Q4 to be attenuated.

The performer can vary the application of this function by depressing the AIS Pedal to less than its full extent, thereby leaving photoconductor PH1 with a substantial resistance value. If the pedal is not depressed at all, the resistance of PH1 may be made sufficiently high so that no attenuation occurs, in spite of the presence of a signal at the "ATTENUATE" input. The choice is left to the performer.

Depending on the presence or absence of an "ATTENUATE" signal and the extent to which the Pedal is depressed, a signal of a predetermined strength appears at the collector of Q4. This signal is the input to the Voice Module illustrated in FIG. 3.

The function of the Voice Module of string A, the circuitry of which is repeated for each other string of the guitar, is to process electronically the amplified signal from the collector of transistor Q4, modifying or amplifying that signal to produce, in this embodiment, six voices from signal A.

Through the parallel combination of capacitor C7 and capacitor C8-resistor R4, signal A is applied to the base of transistor Q9. Capacitor C7 has a small value which serves to boost the high frequency response of the circuit to compensate for any losses and to provide clear high notes. The output of Q9, denominated voice Az, is the natural sound of guitar string A.

Through capacitor C9 signal A is applied to the base of transistor Q10, which amplifies it and applies it both to the primary of transformer T1, and, through capacitor C10, across the parallel combination of reversed diodes D4 and D5. The parallel arrangement of diodes D4 and D5 acts as a limiter in reverse, blocking the middle strength values of the signal and passing the positive and negative peaks intact. The output from the parallel arrangement of diodes D4 and D5, signal A with the middle values removed, becomes voice Av.

Through C8 signal A is also applied to the base of Q11. The collector of Q11 is shunted to ground through a large capacitor C11 leaving a residual sawtooth signal which is coupled to the bases of transistors Q12 and Q13. The amplified sawtooth signal at the collector of Q12 becomes voice Aw and is also applied, together with the input to Q12, through capacitor C12 to the secondary of T1 where it mixes with the other current in the secondary to produce voice Au. The collector of Q13 is coupled through capacitor C13 to the limiter composed of diodes D6 and D7. The resulting signal, a near square wave, is the basis for the other three voices.

Through trimmer resistor R5, transistor Q14 receives a portion of the signal from the limiter composed of D6 and D7 and projects an amplified image of the signal 180° out of phase with the original (because of the nature of a common-emitter transistor amplifier) into the junction of diodes D8 and D9 through D9. The same signal with the original phase comes to that junction directly from the limiter through D8. Diodes D8 and D9 act as a full wave rectifier, and the signal at their junction is raised one octave. The symmetry of the new signal appearing at the junction of D8 and D9 is controlled by potentiometer R5. This new signal is applied to the base of transistor Q15 through the parallel combination of capacitor C14 and resistor R6, which boosts the high frequency components of the signal. The output of Q15 at its collector is voice Ay and also comprises one possible input to transistor Q16.

Transistor Q16 obtains its input from the collector of either Q14 or Q15, depending on the setting of manual switch S1. That is, its input is either the square wave signal from the collector of Q14 or the signal from the collector of Q15, with a very strong second harmonic. Switches similar to S1 are provided in each Voice Module; they allow the performer to choose between two "X" voices for each string independently of the "X" voices chosen for the other strings. The output at the collector of Q16 is voice Ax.

It should be understood that all of the preceding circuitry is repeated for each string, so that, in the present six-string illustrative embodiment, the circuitry shown in FIGS. 2 and 3 is repeated six times. The circuits that follow, on the other hand, are constructed only once.

As is illustrated in FIG. 4, the Mixer comprises six separate amplifier circuits, one for each set of similar voices from the six strings. For clarity, only two are illustrated: the circuit carrying the summation of all the u voices, designated U, and the circuit carrying the summation of all the w voices, designated W. It should be understood that the remaining circuits are identical in design to that for these voices.

The u signals Au, Bu, Cu, Du, Eu, and Fu are all combined and applied through capacitor C16 to the base of transistor Q18. Variable resistors R8 and R9, together with capacitors C17 and C18, control the frequency response of the circuit and hence the tone of the U voice. The amplified output of Q18, voice U, is applied to both the Preset Voice Selector and the Stepping Voice selector. The other Mixer circuits operate similarly. The amplified sawtooth voice W is also used as an input signal to the Percussion Regulator, discussed below. One of the Mixer output signals may also be chosen to drive the Sustain Vibration Amplifier, also discussed below.

The Preset Voice Selector is simply a switch wired to select as its output any one of the six incoming voices, or various combinations of those voices. In the illustrative embodiment, the switch is wired to select any one of U, V, W, X, Y, Z, UY, UZ, VW, VX, WX or WY. These particular outputs are entirely a matter of choice; the ear of the performer being the ultimate decision-maker. Any other outputs could be selected. The output is made available as one input to the Expression Pedal, discussed below.

The Stepping Voice Selector is a stepping relay whose action is controlled by a microswitch actuated by a backward swing of the Expression Pedal. In this illustrative embodiment, the Stepping Voice Selector repeats its cycle every six steps and applies one of the input voices U, V, W, X, Y or Z as a second input to the Expression Pedal.

Footswitch S2 makes available the natural sound of the guitar, voice Z, as a third input to the Expression Pedal, replacing the second input from the Stepping Voice Selector.

The Expression Pedal carries neon bulb NE2 and is designed so that, when the pedal is depressed, NE2 first illuminates only PH3, and then only PH2. The output from the pedal therefore varies from the Stepping Voice Selector signal to the Preset Voice Selector signal as the amount of pedal depression is increased.

The output signal from the Expression Pedal is further processed by the Automatic Gain Control (AGC) circuit and the Percussion Regulator circuit (both shown in FIG. 5) before becoming the ultimate output signal. The signal is applied to the base of transistor Q20 through potentiometer R11 and capacitor C20. Potentiometer R11 should be adjusted to keep the maximum incoming signal below a level which would cause distortion in the second stage transistor, Q21. Through conventional amplifier circuitry the signal becomes available at the collector Q21 for the Volume Pedal and the ultimate output.

Photoconductor PH4 is connected between the collectors of Q20 and Q21, and the bias values to those transistors are adjusted so that their collector voltages are equal and no D.C. current flows through PH4. Since the signal at the collector of Q21 is 180° out of phase with the signal at the collector of Q20, because of the nature of a common-emitter transistor amplifier, if PH4 has relatively low resistance value, the output from Q21 will be attenuated because of negative feedback from the collector of Q21, through PH4, to the base of Q21. On the other hand, if PH4 has a relatively high resistance value, little negative feedback will occur and the output from Q21 will not be attenuated.

The resistance level of PH4 is controlled by neon bulb NE3, located in the collector circuit of pnp-type transistor Q22. A portion of the output signal at the collector of Q21 is applied to the base of transistor Q23 through potentiometer R12, the manually-set AGC level control. Transistor Q23 amplifies the signal and passes it to the rectifier circuit composed of diode D11 and capacitor C21. The signal here is converted to a negative D.C. value indicative of the amplitude of the output signal at the collector of Q23. This negative voltage is then applied to the base of transistor Q22. The negative bias causes Q22 to conduct, sending current through NE3, thereby reducing the resistance of PH4 and, ultimately, attenuating the signal to the Volume Pedal in an amount dependent on the effective resistance value of R12. Therefore, the signal level at the Volume Pedal is regulated by the value of R12.

Potentiometer R12 controls the ratio of the volume of single notes to the volume of chords. Potentiometer R12 should be adjusted so that single notes do not cause NE3 to light and thus do not cause any attenuation of the output signal but that chords, having a much higher RMS value than single notes, make NE3 glow sufficiently to attenuate the output signal to the strength of the single note output signal.

The Percussion Regulator (FIG. 5) takes as its input the sawtooth voice W from the Mixer. Its function is to remove the sharp "click" heard when the guitar pick strikes the strings, thereby making melodies sound bowed rather than struck. It operates by causing each note to be eased into audibility, reaching its full volume about one/half second after the note has been struck.

When the Percussion Regulator is not in operation (i.e., if switch S3 is in its open position), very little current flows through NE3 because of the relatively high resistance in series with NE3. Therefore, in this condition the resistance value of PH4 is relatively high and no attenuation occurs. Closing S3, however, puts Q24 into saturation because of the relatively low resistance path thereby established between B- and its base, and this makes NE3 glow brightly. The glow of NE3 attenuates the output at the Volume Pedal by about 90 percent in the manner described above. When any string is plucked, the W voice derived from that string in the Mixer is applied to the base of transistor Q25 and amplified by Q25 and Q26. The interstage coupling capacitor C22 is made relatively small to accentuate the high frequency components of the signal. This is done in order to compensate voice W for its relative weakness in high frequency components which results from the manner in which voice W was generated, i.e., the presence of capacitor C11 between the collector and the base of transistor Q11.

The output signal from Q26 is rectified by diode D12 into a positive D.C. signal proportional to the strength of the W signal applied. Capacitor C23, of relatively large value, smoothes this signal. This positive signal serves to lower the degree of negative bias at the base of pnp-type transistor Q24, tending to turn this transistor off and thereby dim NE3. Photoconductor PH4 is a comparatively low speed photoconductor, for example a NSL-457, whose frequency response drops off sharply below about 60 Hz, and because of its slow recovery rate and the time delay in the circuit controlling NE3 caused by capacitor C23, the output signal at the collector of Q21 rises gradually in strength from a low level determined by the maximum attenuation available by the action of PH4 to its normal unattenuated level, with the initial percussive attack eliminated from the note. The maximum attenuation is that produced by the lowest attainable resistance value of PH4. Potentiometer R13, at the input to the Percussion Regulator, controls the audible duration of the note and the overall sensitivity of the system.

Capacitor C22, by boosting the deficient high frequency component of voice W, ensures that the Percussion Regulator will operate in the same manner for high and low notes. If the high frequency components were not boosted, voice W for a low note would be a stronger signal than voice W for a high note, and this would cause a low note to rise into audibility more rapidly, last longer, and decay from audibility more rapidly than high note. This would be an undesirable musical characteristic.

The Volume Pedal (FIG. 5) is a neon-photoconductor combination as described above which allows the performer to vary the volume of the output signal.

The circuitry just described possesses an additional advantage. One conventional tone modification device in wide use, known as a "wah-wah" pedal, comprises a passive electrical circuit in series with the output signal of the guitar and including as one element thereof a variable resistance element under the control of the performer. Depending on the instantaneous setting of the resistance, a matter determined by the performer, this device primarily passes only low or high frequencies. In operation, performers attempt to synchronize their depression of the pedal with the playing of the notes, to give each note a similar frequency profile, but this is quite difficult to accomplish.

The present system provides means for obtaining the "wah-wah" effect automatically without relying on the performer's skill. Neon bulb NE3 is illuminated each time a note is struck, and this causes the resistance of photoconductor PH4 to drop each time in the manner described above. If a photoconductor similar to PH4 were placed in series with the output signal and exposed to NE3, the "wah-wah" effect could be achieved automatically.

If the performer desires, a note played on this guitar can be sustained for any desired length of time, at any volume level, in any acoustic environment. This is accomplished, as indicated generally in FIG. 1, by amplifying and shaping one of the "voices" from the string being played and converting the processed signal into a mechanical vibration conveyed back to the string. In the illustrative embodiment shown, the input signal for the Sustain Vibration system is chosen to be the X signal from the Mixer, but another voice could be used if desired.

The Sustain Vibration circuit, shown in detail in FIG. 6, includes a two stage transistor preamplifier of standard design, a limiter made up of diodes D15 and D16, the Sustain Pedal, transformer T2, switch S5, and a power amplifier of standard design feeding the Sustain Vibrator coil. When the Sustain Pedal is depressed, neon bulb NE5 illuminates photoconductor PH6, lowering its resistance and allowing the amplified signal from transistors Q27 and Q28 to pass to the rest of the system. The limiter ensures that, irrespective of the strength of the signal from the Mixer, the signal applied downstream will have a preset strength. This allows the Sustain Vibration system to maintain the same output volume level whether chords or single notes are being played.

When the Sustain function is activated, the amplified signal from the power amplifier is converted into a mechanical vibration conveyed back to the guitar string by apparatus shown in FIGS. 7 and 8. The apparatus, shown in relation to guitar body 50, includes a permanent magnet 51 mounted in the guitar and a coil 52 in movable relationship to the magnet and rigidly attached to the underside of extension 53 of guitar bridge 54. FIG. 7 shows this relationship between the coil and extension schematically. The coil, which conveniently may be several turns of copper wire on a form, receives its signal from the power amplifier. It is free to move with respect to the magnet as much as the flexibility of the extension will allow. Bridge 54, including its extension 53, is commonly made of steel and is securely held in place by supporting posts 55. Strings 56 extend from tailpiece 57, across the bridge 54, over pickups 58, and on to the neck of the guitar.

In operation the presence of a signal in coil 52 causes it to vibrate vertically with respect to magnet 51, rigidly mounted in body 50. These vibrations are transmitted to that part of the bridge in contact with the strings by its extension 53, thereby completing a feedback path of which the guitar string is the frequency determining factor. Operation of this system is totally independent of the output volume level of the guitar and the acoustics of the concert setting.

The coil-magnet combination can be mounted anywhere on the guitar provided only that it is not in the inductive range of the pickups. Furthermore, the coil could transmit its vibrational energy to the strings through a connection other than the bridge extension here disclosed. The system should be designed so that there is no dominant resonant frequency in the coil-string coupling within the frequency range of the strings. In addition, correct phase alignment between the signal at the coil and the signal at the pick-ups should be maintained. Correct alignment is obtained by use of switch S5 and transformer T2. The center tap of the transformer's secondary winding is common and the two extremes are both available, by activation of S5, as alternate sources for the coil driving signal.

With the sustain vibration system in operation, the performer can play with his left hand only, the minute response found naturally in each string, when fed back to the bridge by the mechanical feedback system here disclosed, being sufficient to sustain the note. This can be done without affecting the quality or volume of the ultimate guitar output.

The following are the values of the circuit components used in the illustrative embodiment of my invention previously discussed:

A. Components discussed

R1 470 ohms (Phillips EO97AC series Trimmer Potentiometer) R2 10K ohms (Phillips EO97AC Potentiometer) R3 1K ohms (Phillips EO97AC Potentiometer) R4 120K ohms R5 470K ohms (Phillips EO97AC Potentiometer) R6 24K ohms

R8 500K ohms R9 500 K ohms

R11 47K ohms (Phillips EO97AC Potentiometer) R12 500K ohms R13 100K ohms (Phillips EO97AC Potentiometer) D1 IN270 D100-04 IN270 All other diodes IN4001

c1 300 mf 30v C2A,B 6.4 mf 30v C2C,D 10 mf 30v C2E,F 25 mf 30v C3 25 mf 30v C4A,B,C 0.22 mf 70v C4D,E,F 0.33 mf 70v C5A,B 0.1 mf 70v C5C,D,E 0.22 mf 70v C4F 0.33 mf 70v

C7A,B 680 pf 70v C7C 0.001 mf 70v C7D 0.0015 mf 70v C7E 0.002 mf 70v C7F 0.005 mf 70v C8A,B 0.03 mf 70v C8C,D 0.05 mf 70v C8E,F 0.068 mf 70v C9A,B 0.01 mf 70v C9C 0.02 mf 70v C9D 0.02 mf 70v C9E 0.033 mf 70v C9F 0.05 mf 70v C10A 0.05 mf 70v C10B,C,D 0.1 mf 70v C10E 0.133 mf 70v C10F 0.168 mf 70v C11A,B 25 mf 70v C11C,D,E 50 mf 70v C11F 100 mf 70v C12A 0.01 mf 70v C12B 0.015 mf 70v C12C,D 0.02 mf 70v C12E 0.03 mf 70v C12F 0.033 mf 70v C13A,B 0.05 mf 70v C13C 0.168 mf 70v C13D 0.2 mf 70v C13E 0.22 mf 70v C13F 0.1 mf 70v

C14A,B,C 0.02 mf 30v C14D 0.25 mf 30v C14E,F 0.03 mf 30v

C16 6.4 mf 25 v C17 0.005 mf 70v C18 0.01 mf 70v

C20 6.4 mf 25 v C21 16 mf 25 v C22 0.1 mf 70v C23 2.5 mf 25 v

Q1 2N3415 Q2 2N3415 Q3 2N3415 Q4 2N3415 Q5 2N2711 Q6 2N2711 Q7 2N2430 Q8 2N2430 Q9 2N3415 Q10 2N3415 Q11 2N3415 Q12 2N3415 Q13 2N3415 Q14 2N3415 Q15 2N3415 Q16 2N3415 Q18 2N3415 Q20 2N3415 Q21 2N3415 Q22 2N4412 Q23 Q24 2N3415 Q25 2N3415 Q27 2N3415 Q28 2N3415

b. components not specifically discussed

70 100K ohms 71 3K ohms 72 33K ohms 73A,B no resistor 73C,D,E,F 22K ohms 74 2.2M ohms 75 39K ohms 76 510 ohms 77 100 K ohms 78 13K ohms 79 82K ohms 80 75K ohms 81 100K ohms 82 18K ohms 83 120 ohms 84 120K ohms 85 0.1 mf 70v 86 20 mf 25v 87 3 mf 25v 89 610 ohms 90 0.02 mf 30 v 91 30K ohms 92 68K ohms 93 8.2K ohms 94 3.6K ohms 95 36K ohms 96 11K ohms 97 680K ohms 98 15K ohms 99 4.3K ohms 100 100 ohms (Phillips EO97AC Potentiometer)

110 120K ohms 111 5.6K ohms 112 68K ohms 113 470K ohms 114 51K ohms 115 20K ohms 116 9.1K ohms 117 56K ohms 118A,B,C, 1.6 mf 70v 118D,E, 2.5 mf 70v 118F 6.4 mf 70v 119 100K ohms 120 3.3K ohms 121 62K ohms 122 100K ohms 123 6.8K ohms 124 110K ohms 125A,B,C, 1.6 mf 70v 125D,E 2.5 mf 70v 125F 6.4 mf 70v 126 15K ohms 127 2K ohms 128 130K ohms 129 130K ohms 130 360K ohms 131A,B, 0.02 mf 70v 131C 0.03 mf 70v 131D 0.04mf 70v 131E 0.05 mf 70v 131F 0.07 mf 70v 132 4.7K ohms 133 100K ohms 134 68K ohms 135 1.3M ohms 136 82K ohms 137 100K ohms 138 3K ohms 139 43K ohms 140 270K ohms 141 47K ohms 142A,B, 1.2M ohms 142C,D 910K ohms 142E,F 1M ohms 143 1K ohms 144 91K ohms 145 75K ohms

150 2K ohms 151 160K ohms 152 16K ohms 153 12K ohms 154 6.4mf 25v 155 20K ohms 156 6.4 mf 25v 157 62K ohms 158 47K ohms

160 14K ohms 161 3.9K ohms 162 56K ohms 163 470 ohms 164 0.33 mf 70v 165 56K ohms 166 3.9K ohms 167 470 ohms 168 6.4 mf 25v 169 62K ohms 170 3K ohms 171 1K ohms 172 100 mf 64v 173 36K ohms 174 36K ohms 175 6.4 mf 25v 176 56K ohms 177 3K ohms 178 39K ohm 179 56K ohms 180 3K ohms 181 33K ohms 182 6.4 mf 25v 183 7.5K ohms 184 62K ohms 185 560 ohms 186 5.6K ohms 187 7.5K ohms 188 300K ohms 189 10M ohms 190 560 ohms 191 100K ohms (Phillips EO97AC Potentiometer) 192 91K ohms 193 100K ohms 194 110K ohms 195 39K ohms 196 43K ohms 197 8.2K ohms 198 6.4 mf 25v 199 33K ohms 200 56K ohms 201 2.7K ohms 202 0.22 mf 70v

210 43K ohms 211 56K ohms 212 3K ohms 213 33K ohms 214 0.22 mf 70v 215 470K ohms (Phillips EO97AC Potentiometer) 216 56K ohms 217 3K ohms 218 33K ohms 219 6.4 mf 25v 220 62K ohms 221 10K ohms 222 6.4 mf 25v 223 1600 mf 64v

Miscellaneous

R8/r9 is an ohmite dual potentiometer No. CCU-5041.

All neons are AIA.

All photoconductors are Phillips B8-731-05 except PH4, which is an NSL-457.

The transformers T1 and T2 are both Armaco At-46.