https://www.emusic-diy.org/ 2026-05-13T13:39:44+00:00 https://www.emusic-diy.org/ https://www.emusic-diy.org/_media/wiki:dokuwiki.svg text/html 2024-07-29T00:17:41+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.emusic-diy.org/penfoldbookchapter2:eg?rev=1722212261&do=diff <<- Back ^- Intro -^ Forward ->> Chapter 2: EG THE EG Envelope Generators If reduced to its most fundamental form an attack-decay envelope generator need have no more than five components plus some keyboard switches, as shown in the circuit diagram of Figure 11. This requires two sets of keyboard switches, one set which are normally open and another set which are normally closed. Note that with this circuit, and with the other envelope generators described here, the switches which activa… text/html 2024-07-29T00:13:57+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.emusic-diy.org/penfoldbookchapter2:keyboard?rev=1722212037&do=diff <<- Back ^- Intro -^ Forward ->> Chapter 2: Keyboard THE KEYBOARD Keyboard circuits can be quite complex and difficult to set up, but good results can be obtained using a very basic type such as the one shown in the circuit diagram of Figure 8. The first requirement is for a potential divider to generate all the voltages for the required notes. These voltages are provided by RV3 plus R10 to R17, but only eight fixed resistors are shown in Figure 8 for the sake of clarity. In practice th… text/html 2024-07-29T00:22:38+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.emusic-diy.org/penfoldbookchapter2:lfo?rev=1722212558&do=diff <<- Back ^- Intro -^ Forward ->> Chapter 2: Noise Generator The LFO LFO The use of an LFO (low frequency oscillator) for frequency modulating a VCO to give the vibrato effect was mentioned in Chapter 1. LF0s can actually be used in 'other ways, such as providing one of the voltage sources for a VCF in order to give dynamic effects. It is well worthwhile having one or two LF0s in the system and experimenting with these. Figure 23 shows the circuit diagram for a simple LFO. text/html 2024-07-29T00:20:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.emusic-diy.org/penfoldbookchapter2:mixer?rev=1722212456&do=diff <<- Back ^- Intro -^ Forward ->> Chapter 2: Mixers Mixers VCF Mixer The modules described so far are the main building blocks of a synthesiser, but a practical instrument usually has some additional circuits. Just what additional circuits are required depends on the way in which the main modules are to be interconnected and used, and on how many of these modules the instrument is to incorporate. Anyway, the circuits described in the following section of this book should prove useful in g… text/html 2024-07-29T00:21:50+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.emusic-diy.org/penfoldbookchapter2:noisegen?rev=1722212510&do=diff <<- Back ^- Intro -^ Forward ->> Chapter 2: Noise Generator The Noise Generator Noise Generator Not all synthesisers incorporate a noise generator, but it is certainly a circuit which I would never omit from one. In this context the noise we are talking about is of the “white text/html 2024-07-29T00:19:53+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.emusic-diy.org/penfoldbookchapter2:psu?rev=1722212393&do=diff <<- Back ^- Intro -^ Forward ->> Chapter 2: PSU THE PSU Power Supply Unit To power the circuits described in this chapter a power supply capable of supplying + 12 volts and - 12 volts is required, and the supply must be well smoothed and stabilised. The maximum current required depends on which modules are used, and on how many of each one are incorporated into the instrument. For a simple single oscillator type the current consumption is likely to be less than 100 milliamps from both su… text/html 2024-07-29T00:14:44+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.emusic-diy.org/penfoldbookchapter2:vca?rev=1722212084&do=diff <<- Back ^- Intro -^ Forward ->> Chapter 2: VCA THE VCA VCA Circuit The circuit diagram of the VCA appears in Figure 10. This is based on one of the transconductance amplifiers in an LM1360ON or LM1370ON (IC7), and unlike the previous circuits this one operates from a single 12 volt positive supply rather than dual balanced 12 volt supplies. R19, R20, and C13 are used to provide a centre tap on the supply for biasing purposes. The VCA is an entirely conventional type which makes use of t… text/html 2024-07-29T00:19:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.emusic-diy.org/penfoldbookchapter2:vcf?rev=1722212354&do=diff <<- Back ^- Intro -^ Forward ->> Chapter 2: VCF THE VCF VCF Figure 17 shows the circuit diagram of the VCF. Like the VCA, this should have its control input driven by way of the logarithmic to linear converter (Figure 7). Also in common with the VCA, this circuit is based on the two transconductance amplifiers and buffer stages in an LN1360ON or LM1370ON. The circuit consists of two single stage lowpass filters connected in series. In the first of these IC11a acts as a voltage controll… text/html 2024-07-29T00:07:34+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.emusic-diy.org/penfoldbookchapter2:vco?rev=1722211654&do=diff <<- Back ^- Intro -^ Forward ->> Chapter 2: VCO THE VOLTAGE CONTROLLED OSCILLATOR The basis of any analogue synthesizer is its VCO (or VCOs), and this is the module that we will consider first. The circuit diagram of the VCO appears in Figure 6. IC1 is an LM13600N dual transconductance amplifier (or the virtually identical LM13700N), and devices of this type are much used in electronic music. What makes transconductance amplifiers so useful is their ability to operate as a sort of voltag…