Simple Frequency Doubler Circuit

This is a simple three transistor frequency doubler circuit to raise an audio frequency by a factor of two i.e., one octave.
O1 is connected as a phase splitter with anti-phase signals·’ appearing at its collector and emitter. These signals are fed to two emitter followers Q2 and O3, which have a common emitter resistor, and thus add the two anti-phase signals. A degree of distortion is inevitable as shown in Fig. 2, but is acceptable for speech and soloists and produces a sound similar to the Chipmunks or Pinky and Perky. 

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22 Watts Mini Subwoofer Circuit TDA1516 with Adjustable Frequency

The subwoofer is a subwoofer or a speaker to reproduce low frequencies, devotee of 20 Hz to 150 Hz electronic circuit diagram below shows the details of a scheme of the main amplifier TDA1516 22 watt in 4 ohm car subwoofer driver. This device is designed for an existing stereo amplifier, often requires adding another blow to the music of driving a subwoofer.

The amplifier uses BTL is a good and cheap ((Bridge Tied Load channels) 13-pin IC TDA1516 from Philips is now NXP Semiconductors), which may provide a small number of components and 22W at 4 ohm load voltage 12 volt car battery default.

The device consists of several parts: the name of the potentiometer, dual-linear motion potentiometers, 1/4W resistors, capacitors, electrolytic 25V, 63V Polyester capacitors, LED, 100 mA NPN transistor, dual BIFET Op-Amp, 24 W BTL car radio RCA audio input amplifier and two speakers 4 ohm or 8 ohm woofers in isobaric parallel wiring.

DIY 12 volt car project Subwoofer frequency low-pass filter circuit and BTL Amplifier TDA1516

The signals from the line outputs for stereo mixing amplifier input drive, and taking into account the level of the signal to the buffer and can be reversed IC1A phase SW1. Such control may be useful to the subwoofer in phase with the speaker of the existing car radio.

Then, a variable frequency 12dB/octave-pass low IC1B, the components of the Q1 and then you can pass the low frequency of 70 Hz or 150 Q2, R17 and C9 form a voltage stabilizer to facilitate access and filtering circuit to prevent track of the services given power at a low level positive.

LPF subwoofer and amplifier parts list:

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Potentiometer
P1-10K
P2-22K

Resistor
R1, R4-1K
R2, R3, R5, R6-10K
R7, R8-100K
R9, R10, R13-47K
R11, R12-15K
R14, R15, R17-47K
R16 6K8
R18-1K5

Capacitor
C1, C2, C3, C6-4μ7 25V
C4, C5-68NF 63V
C7 33nF 63V
C8, C9 220μF 25V
C10 470nF 63V
C11 100nF 63V
C12 2200uF 25V

Diode
D1 LED Lamp

Transistor
Q1, Q2 BC547

IC
IC1-TL072 Op-Amp
IC2-TDA1516BQ Car Amplifier 24 Watt BTL

Switch
SW1-Toggle SPDT
SW2-Toggle SPDT

RCA Jack
J1, J2 RCA Audio Input

SubWoofer Drive Unit
4-ohm woofer driver or two 8 ohm woofers connected to Isobaric  Read More

Sine Wave Generator 1KHz Frequency

This is iKHz sine wave generator schema built based on configuration of inverted Wien bridge (see C1-R3 & C2-R4). R5 and R7 used for output amplutide setting. Set R5 to read 1V RMS on an Audio Millivoltmeter connected to the output with R7 rotated fully clockwise, or to view a sinewave of 2.828V Peak-to-Peak amplitude on the oscilloscope.

Component list:

R1____________5K6 1/4W Resistor
R2____________1K8 1/4W Resistor
R3,R4________15K 1/4W Resistors
R5__________500R 1/2W Trimmer Cermet
R6__________330R 1/4W Resistor
R7__________470R Linear Potentiometer

C1,C2________10nF 63V Polyester Capacitors
C3__________100µF 25V Electrolytic Capacitor
C4__________470nF 63V Polyester Capacitor

Q1,Q2_______BC238 25V 100mA NPN Transistors
LP1___________12V 40mA Filament Lamp Bulb (See Notes)
J1__________Phono chassis Socket
SW1__________SPST Slider Switch
B1_____________9V PP3
Clip for 9V PP3 Battery

Notes:

• The bulb must be a low current type (12V 40-50mA or 6V 50mA) in order to obtain good long term stability and low distortion.
• Using a bulb differing from specifications may require a change of R6 value to 220 or 150 Ohms to ensure proper diagram oscillation.
• With C1, C2 = 100nF the frequency generated is 100Hz and with C1, C2 = 1nF frequency is 10KHz but R5 requires adjustment.
• High gain transistors are preferred for better performance.

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Light to Frequency converter circuit

Here is the schema diagram of a effective light to frequency converter schema that can be used for variety of applications such as light intensity measurement,fun etc.






The schema is based on TLC555, the CMOS version of famous timer IC NE 555. A photo diode is used for sensing the ligt intensity.The timer IC is wired in astable mode.The leakage current of the reverse biased photo diode is proportional to the light intensity falling on it.This leakage current charges the capacitance C1.When the capacitor voltage reaches 2/3 of the supply voltage the out put (pin 3) goes low.As a result the capacitor discharges through photo diode .When the capacitor voltage reaches 1/3 the supply voltage the out put (pin 3) of IC goes high.This cycling continues and we get a frequency at pin 3 proportional to the light intensity falling on the photo diode.


Notes.

* With the given components the frequency varies from 1KHZ @ complete darkness to 24 Khz @ bright sunlight.The frequency range can be changed by using different values for C1.

* Use any general purpose photo diode for D1.

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Discrete Sliding Tone Frequency Ramp Doorbell

This Discrete Sliding Tone (Frequency Ramp) Doorbell schema produces a low tone that will slide up to higher frequency. The equivalent total resistance connected between the base of Q1 and ground (Rbg) , and coupling capacitor  C1  determines the AF oscillator’s frequency. The resistance (Rbg) is equal to (R2+R1)R3.  

Here is the schematic diagram of the schema. The R2 is used to set the initial bias condition, adjusted to produce a pleasant low starting frequency doorbell tone. D1 will start to conduct when Capacitor C3 charge through R6 until it reaches D1 bias  voltage level. 

Then the value of Rbg is paralleled by R4 and D1, and R5-D2-D3, and the values of diode’s equivalent resistance is gradually decreased as the C3 voltage ramp up.  This decreasing resistance value make the output tone slides up in frequency.  Two different diode path is provided to extend the linear area of diode conduction transition slope. With two path with different biases, after the single diode path has saturated, the second path provide further linear increase at higher voltage level.

 Discrete Sliding Tone (Frequency Ramp) Doorbell Circuit

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