EG Using NE555|
At first, you should better check this page for the basic operation of EG.
(it's one of MR. tanaka's pages. He write his all pages in Japanese . if you can't read them, you should better use this service(AltaVista - Babel Fish Translation))
"1: Principle AR type EG " may be good reference for you.
the Most first module that I assembled
Most important point is
getting gether electricity through resistor onto the capacitor, and
throwing away them through resistor.It can change the speed to do that.
Big value of resistance is not easy to run through for electricity, or small
value of them can discharge it easily. it may change their speed.
the changeing voltage can be seen over the output buffer that has high input impedance.
NE555 have compalater and easy switch. they will make them easy to checking the moving voltage and switching
and they will possible to form EG relatively simply.
As for the data seat of NE555
the 4th page of "1.Basic Operating Table" is the chart what we want to learn.
You may also need this schematics to verify
Second ADSR Schematic
Let's check the action of EG dividing in 4 period called attack, decay,
Susteen and Release.
- Making triger at the moment we get input gate, and put it into
(2pin) of NE555.
- Making the voltage which does not depend on input level by transistor and
put it in to reset of NE555 (4pin).
- Discharge of NE555 (7pin) will open. (in many cases, it's the same state as staring)
there is no voltage difference at the both ends of the susteen volume, so there is no
- Output (3pin) becomes on, setting of the attack time pot passes the voltage for attack and charges the capacitor.
Attack period will ends by getting voltage threshold. it is 2/3 VCC. this value is set
in the NE555.
- When the Attack period ends, output (3pin) becomes off. there is no voltage to charge the capacitor
- Discharge (7pin) becomes on,(electricity flows to GND, voltage of the both ends of the susteen volume come back.
- At this point the voltage is higher than susteen level so it get start to discharge.and its speed is decided by the resistance of decay.
- Attack period will ends by getting voltage is same as susteen.
The same state will continues untill input gate has been entered.
making Susteen voltage is the core of this methods
- When the input gate ends, discharge (7pin) becomes
off this the signal which reverses reset (4pin) entering, and susteen voltage becomes off.
- Output (3pin) dose not chenge its state (it is off)
- Diode controlle the flows and release pot may change the speed to discharge.
electricity in the capacitor may throw away into the emitter of the transistor inside of NE555.
EG may have big infruence for playng keyboard style. and I think that small mod is one of presure of DIY.
Decay level going down to the susteen level. and its flows is controled by diode. so we can change the susteen level up word only. RadioJunkBox add the mod by only 1 FET to be able to change the susteen levels.
his top page is here. You should better to check the page about moduler synth that have prohet5 like panels its so nice!