Multiple Feedback Filter Using Differential Low Pass Filter Circuit

This is a circuit for low pass filter that can be used for multiple feedback filter. The filter is a two pole filter topology used to implement an electronic filter by adding two poles to the transfer function. This is available in a low pass, high pass, band pass, and notch versions, although the band pass and notch versions are not recommended because of the low resistor values. Some Feedback filters are useful for distribution, analysis and other tasks such as the Sound to light converter or a fully functional Vocoder. This is the figure of the circuit.


The circuit above shows an example of Multiple Feedback Filter with Differential Low Pass Filter Circuit Schematic Diagram. The table below contains details of the transfer functions (Bessel, Butterworth, and Chebyshev 3 dB).
Bessel
For = 1 / (2pRC)
R1 = R2 = 0.625R
R3 = 0.36R
C1 = C
C2 = 2.67C
Butterworth
For = 1 / (2pRC)
R1 = R2 = 0.65R
R3 = 0.375R
C1 = C
C2 = 4C
Chebyshev 3 dB
For = 1 / (2pRC)
R1 = 0.644R
R2 = 0.456R
R3 = 0.267R
C1 = 12C
C2 = C

Preamp And Tone Control Circuit Using Transistor

This is a design circuit for preamp and tone control circuit that is can be combine in single board. This circuit is control by transistor. This is the figure of the circuit.


To control the volume level is by P1 and to control Bass level is by P2 and to control the Treble is by P3. This circuit is o mono channel preamp and tone control circuit. [Circuit source : Free Circuit Diagram.IRone.com Notes].

40 LED Bicycle Circuit Light Using 555 Timer IC

This is the circuit for flashing the bicycle light circuit that is powered with four AA cells (DC 6 volts). This circuit is controlled by timer IC that is 555 Timer IC and transistor. Two sets of 20 LEDs will alternately flash at approximately 4.7 cycles per second using RC values shown (4.7K for R1, 150K for R2 and a 1uF capacitor). This is the figure of the circuit.


The time intervals for the two lamps are about 107 milliseconds (T1, upper LEDs) and 104 milliseconds (T2 lower LEDs). Two transistors are used to provide additional current beyond the 200 mA limit of the 555 timer. A single LED is placed in series with the base of the PNP transistor so that the lower 20 LEDs turn off when the 555 output goes high during the T1 time interval. The high output level of the 555 timer is 1.7 volts less than the supply voltage. Adding the LED increases the forward voltage required for the PNP transistor to about 2.7 volts so that the 1.7 volt difference from supply to the output is insufficient to turn on the transistor. Each LED is supplied with about 20 mA of current for a total of 220 mA. The circuit should work with additional LEDs up to about 40 for each group, or 81 total. The circuit will also work with fewer LEDs so it could be assembled and tested with just 5 LEDs (two groups of two plus one) before adding the others.