Showing posts with label effect. Show all posts
Showing posts with label effect. Show all posts
Monday, September 8, 2014
Guitar Reverb Effect
Description
The guitar input stage is a class A amplifier with adjustable bias. A 2N3906 PNP tranistor is used for a low noise design on this stage. The output of the preamp stage is sent to three places: the output mixer amp, the reverb driver amp, and the input clipping detector.
The reverb driver amp consists of a phase inverting push-pull circuit made from dual sections of a 5532 high quality audio op-amp. This provides a voltage swing of approximate twice the supply voltage to the reverb impedance matching transformer, allowing higher power transfer. The 100 ohm resistor is critical for insuring a clean drive signal, without it, the op-amps can saturate when driving the transformer, producing unwanted distortion.
The transformer matches the impedance of the driver amplifer to the reverb driver coil and allows a dual phase driving signal to power a reverb coil with one grounded side. The transformer is a standard "70 volt" audio line transformer that is often found on PA systems. One reader reported having good results using a Mouser 42TU013 (1K to 8 ohm) transformer. If you can find a reverb tank with a high impedance driver coil, the transformer may be eliminated, the driver coil will require isolation from ground.
The output of the reverb tank is sent to the reverb recovery amp, it is also a 2N3906 class A low noise stage.
The mixer amplifier is a 2N3904 transistor biased for class A operation. It mixes the dry signal from the input preamplifer with the wet signal from the reverb recovery amp through two 10K resistors. The wet signal level is adjusted by a 10K potentiometer.
The clipping detector stages receive inputs from the guitar preamp and the reverb recovery amp, they act in an identical manner. The 1458 op-amp is wired as a comparator with a threshold that is near the high side of the allowable voltage swing on the associated 2N3906 preamp stage. If the transistor output exceeds this voltage, the 1458 output turns on, causing the 4011 one-shot pulse stretcher circuit to fire. The one-shot circuit activates the LED, and stays on long enough that even minor clipping on the amplifier causes visible blinking.
The power supply filter involves an RC filter between the DC input and the VF1 power bus. VF1 drives the reverb driver, the output amp, and the clipping circuit. VF2 and VF3 are further filtered with their own RC filters, they provide isolated DC for powering the input preamp and reverb recovery amplifier stages.
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| Guitar Reverb Effect Circuit |
Original article sourse solorb.com
Tuesday, August 26, 2014
DIY Tremolo Effect
This tremolo effect schema uses the XR2206 and the TCA730 IC which is designed as an electronic balance and volume regulator with frequency correction. The schema is use full for stereo channels and it also has the ability to simulate the Lesley effect aka rotating loudspeaker effect.
How does the Tremolo Effect Circuit works:
Balance and volume settings are done with a linear potentiometer for both channels. If this potentiometer is replaced with an AC voltage source, a periodic modulation of the input signal can be achieved. This AC voltage source comes from the function generator IC XR2206. This IC generates square, triangle and sine wave signals but for this project we use only the sine wave.
IC Tremolo Effect Circuit diagram
The modulation voltage can be varied with P1 from 1 Hz up to 25 Hz. Resistor R3 sets the operation level of the sine wave generator. R5 and R6 set the DC voltage and the sine wave amplitude at the output. C2 is a ripple filter. The square wave output of the XR2206 drives T2 and a LED to optically display the frequency.
The modulating voltage reaches pin 13 of TCA730 via P3 and R10. This input functions as the volume control or in this case the volume modulation. The degree of the balance modulation (Lesley effect) can be varied with P2. A regulated power supply using 7815 IC is recommended. Do not use a non-stabilized power supply since the current variations would influence the modulation negatively.
Attach the 7815 IC to a good heat sink (about 10 cm2).
How does the Tremolo Effect Circuit works:
Balance and volume settings are done with a linear potentiometer for both channels. If this potentiometer is replaced with an AC voltage source, a periodic modulation of the input signal can be achieved. This AC voltage source comes from the function generator IC XR2206. This IC generates square, triangle and sine wave signals but for this project we use only the sine wave.
IC Tremolo Effect Circuit diagram
The modulating voltage reaches pin 13 of TCA730 via P3 and R10. This input functions as the volume control or in this case the volume modulation. The degree of the balance modulation (Lesley effect) can be varied with P2. A regulated power supply using 7815 IC is recommended. Do not use a non-stabilized power supply since the current variations would influence the modulation negatively.
Attach the 7815 IC to a good heat sink (about 10 cm2).
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