Wednesday, January 26, 2011
TONE CONTROL AND SUBWOOFER OUT
PT2350 is a tone control subwoofer cross-over low pass filter chip utilizing CMOS Technology. It features a tone control range of + 10dB (50Hz, 4 KHz) and subwoofer low pass filter of the second order Sallen Key Design. The roll-off point can be adjusted by changing the value of the external capacitor. Pin assignments and application circuits are optimized for easy PCB Layout and cost saving advantages.
CMOS Technology
2-Channel Input
3-Channel Output (Including 1 stereo Output and Subwoofer Output)
Low Total Harmonic Distortion (THD<0.01%, Subwoofer THD<0.2%)
High S/N Ratio (S/N Ratio <-87dB, A-weighting)
Least External Components
Adjustment of Frequency response by changing the value of the external component
Single Power Supply: 3 to 8.5 Volts
Available in 20 pins, DIP or SO Package
PARTS
Resistors
2------ R1,R2-------------- --------- 10k / 1% / metal film
Capacitors
2------ C9,C10------------- -------- 4.7nF / 63V / polyester
3------ C1,C7,C8-------- -------- --- 47nF / 63V / polyester
1------ C16---------------- --------- 100nF / 63V / polyester
1------ C13----------------- -------- 220nF / 63V / polyester
2------ C3,C4------------- --------- 2.2uF / 50V / polyester
5------ C5,C6,C11,C14,C15--- 3.3uF / 100V / electrolytic
1------ C12------------------------- - 10uF / 35V / electrolytic
1------ C17----------------- --------- 100uF / 16V / electrolytic
1------ C2---------------------------- 470uF / 35V / electrolytic
Integrated Circuits
1------ U1---------------------------- 78L08 / +8V voltage regulator / TO-92
1-------U2---------------------------- PT2350 / stereo tone control, subwoofer low pass filter IC / DIP20
Diodes
1------ D1---------------------------- 1N4153
Miscellaneous
1------ J1----------------------------- 2 pole wire connector (terminal block) to pcb / raster r. 5 mm / hight 9.7 mm
1------ P1----------------- ----------- 10k log stereo potentiometer / 6 mm saft
2------ P2,P3------------------------ 100k lin stereo potentiometer / 6 mm saft
5------ J2 to J5---------------------- RCA female to PCB, straight, Hosiden any colour
NOTICE ABOUT J2 to J18 . if you make one stereo input device you need 5 pcs of RCA female as listed in parts list
If you make 2 x 6 input device, you need total quantity of 15 pcs RCA female and also 2 x 6 changeover switch.
Code of J2 to J18 RCA female to PCB, straight, Hosiden, any colour
SW1 2 x 6 changeover High quality DIP rotary switch to PCB 2 x 6, Alcos witch DRS 2-6, 3.2mm saft
Frequency response of tone control unit is flat between 20 Hz … 20 kHz when treble and bass pots are in middle.
Overall gain is approx. 6 dB when treble and bass pots are in middle.
Treble and bass tone control range is approx. 10 dB (50Hz / 4 kHz) with given component values.
Subwoofer cut off frequency can be adjusted by bass potentiometer… with component values as listed above it is as follows : bass pot in minimum (left) -3dB point, 240 Hz / -12dB 450 Hz, bass pot (middle) -3dB point 100 Hz /-12dB 200 Hz, bass pot maximum (right) -3dB point 60 Hz / -12dB 120 Hz.
Distortion was < 0.1 % when input level was < 0.3V rms.
There is no balance adjustment potentiometer in this application, if you need balance, you must add it separately in this device.
Thursday, January 20, 2011
LS7220 Simple Electronic Combination Lock
This is the circuit of electronic combination lock based on IC LS7220. This circuit can be used to activate a relay for controlling (on/off) any device when a preset combination of 4 digits are pressed.
[read here...]
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| LS7220 Simple Electronic Combination Lock Circuit |
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| IC LS7220 Pin-Out |
To set the combination Lock, connect the appropriate switches to pin 3,4,5 and 6 of the IC through the header.As an example if S1 is connected to pin 3, S2 to pin 4 , S3 to pin 5, S4 to pin 6 of the IC ,the combination will be 1234.This way we can create any 4 digit combinations.Then connect the rest of the switches to pin 2 of IC.This will cause the IC to reset if any invalid key is pressed , and entire key code has to be re entered.
When the correct key combination is pressed the out put ( relay) will be activated for a preset time determined by the capacitor C1.Here it is set to be 6S.Increase C1 to increase on time.
For the key pad, arrange switches in a 3X4 matrix on a PCB.Write the digits on the keys using a marker.Instead of using numbers I wrote some symbols!.The bad guys will be more confused by this.
UM66 Simple Melody Doorbell
Here is a very simple and low cost to build doorbell circuit using IC UM 66. The UM66 series are CMOS IC’s designed for using in calling bell, phone and toys. It has a built in ROM programmed for playing music. The device has very low power consumption.Thanks for the CMOS technology.
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| UM66 Simple Melody Doorbell Circuit |
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| UM 66 Pin-Out |
If S1 once the push button is pressed C1 is charged and the transistor Q2 will keep the IC playing the music till it ends.The time for the IC to play depends on discharging time of C1 which can be set by R1.Set R1 to select your time ,whether full tone or a part in one press.Transistor Q2 drives the speaker.
Ding dong Doorbell Circuit Using IC 8021-2
This simple and low cost ding dong electronic doorbell circuit is Using IC 8021-2. The IC has an in-built circuitry to produce ding dong sound each time its pin 3 is pulled low. If you try to press switch S2 a second time when the first ding dong sound is still being produed, it has no effect whatever and the two ding-dong bell sounds will be invariably produced.S1 is the ON- OFF switch.
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| Ding dong Bell Dor Circuit |
You may either use a piezo tweeter or an 8-ohm, 500mW speaker at the output. During the standby period, the IC consumes nominal current of a few microamperes only. Therefore switch S1 may be kept closed. Each time switch S2 is pressed, ding dong sound is produced twice. If you try to press switch S2 a second time when the first ding dong sound is still being produed, it has no effect whatever and the two ding-dong bell sounds will be invariably produced.
Simple Doorbell Circuit Using LF351 Op-Amp
This is a electronic doorbell circuit schematic has a very simple function and is very easy to build. This door bell circuit use a LF351 operational amplifier and other few common electronic components . When the S1 push-button is depressed an initial positive voltage is placed on the C2 and the non-inverting terminal of the LF351 operational amplifier and the circuit will oscillate at a low frequency .
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| Dor Bell Circuit Using LF351 Op-Amp |
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| LF351 Pinout |
Simple Electronic lock Circuit Using IC 555
A simple electronic key code lock circuit that require few external components can be constructed using this project. This electronic lock circuit is based on a common 555 timer circuit and some other common components .
This low cost key code circuit use six switches that needs to be pressed to open the lock, but only two switches at a time. In many other , more expensive electronic circuits the key code is formed by pressing some switches one by one , not like in this case two switches . If you don’t like to press two switches in the same time you can eliminate one switch , but in that case the code can be more easy to guess by someone ells. Thus a total of three sets of switches have to be pressed in a particular sequence. (Of these three sets, one set is repeated.)
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| Simple Electronic lock Circuit Using IC 555 |
Pin 2 of 555 timer is the triggering input pin which, when held below 1/3 of the supply voltage, drives the output to high state. The threshold pin 6, when held higher than 2/3 of the supply voltage, drives the output to low state. By applying a low-going pulse to the reset pin 4, the output at pin 3 can be brought to the quiescent low level. Thus the reset pin 4 should be held high for normal operation of the IC.
Three sets of switches SA-SC, S1- S8 and S3-S4 are pressed, in that order, to open the lock. On pressing the switches SA and SC simultaneously, capacitor C3 charges through the potential divider comprising resistors R3 and R4, and on releasing these two switches, capacitor C3 starts discharging through resistor R4. Capacitor C3 and resistor R4 are so selected that it takes about five seconds to fully discharge C3.
Depressing switches S1 and S8 in same time, within five seconds of releasing the switches SA and SC, pulls pin 2 to ground and IC 555 is triggered. The capacitor C1 starts charging through resistor R1. As a result, the output (pin 3) goes high for five seconds . Within these five seconds, switches SA and SC are to be pressed momentarily once again, followed by the depression of last code-switch pair S3-S4.
These switches connect the relay to output pin 3 and the relay is energised. The contacts of the relay close and the solenoid pulls in the latch (forming part of a lock) and the lock opens. The remaining switches are connected between reset pin 4 and ground. If any one of these switches is pressed, the IC is reset and the output goes to its quiescent low state. The given circuit can be recoded easily by rearranging connections to the switches as desired by the user.
Simple Traffic Light Using 4017 Counter
This circuit operates red, kuning and green LEDs in the correct sequence for a single traffic light. The time taken for the complete red - red & amber - green - amber sequence can be varied from about 7s to about 2½ minutes by adjusting the 1M preset. Some amber LEDs emit light that is almost red so you may prefer to use a yellow LED.
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| Simple Traffic Light circuit |
The 555 astable circuit provides clock pulses for the 4017 counter which has ten outputs (Q0 to Q9). Each output becomes high in turn as the clock pulses are received. Appropriate outputs are combined with diodes to supply the amber and green LEDs. The red LED is connected to the ÷10 output which is high for the first 5 counts (Q0-Q4 high), this saves using 5 diodes for red and simplifies the circuit.
List Component of Simple Traffic Light Circuit
- Resistors : 470 ×3, 22k, 100k
- Capacitors : 0.1µF, 1µF 16V radial, 10µF 16V radial
- Diodes : 1N4148 ×6
- LEDs : red, amber (or yellow), green
- 1M preset, horizontal
- 555 timer IC, such as NE555
- 4017 counter IC
- on/off switch
LDR Light sensitive Alarm
The circuit detects a sudden shadow falling on the light-sensor and sounds the bleeper when this happens. The circuit will not respond to gradual changes in brightness to avoid false alarms. The bleeper sounds for only a short time to prevent the battery running flat. Normal lighting can be used, but the circuit will work best if a beam of light is arranged to fall on the light-sensor. Breaking this beam will then cause the bleeper to sound. The light sensor is an LDR (light-dependant resistor), this has a low resistance in bright light and a high resistance in dim light.
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| LDR Light sensitive Alarm Circuit |
Note:
- The light-sensitivity of the circuit can be adjusted by varying the 100k preset.
- The length of bleep can be varied from 0.5 to 10 seconds using the 1M preset.
Using the 7555 low-power timer ensures that the circuit draws very little current (about 0.5mA) except for the short times when the bleeper is sounding (this uses about 7mA). If the circuit is switched on continuously an alkaline PP3 9V battery should last about a month, but for longer life (about 6 months) you can use a pack of 6 AA alkaline batteries.
Audio Peak Level Indicator by Op-Amp LM324
This circuit was designed to provide a valuable test equipment tool for sound reinforcement systems like guitar amplifiers and the like. Used in conjunction with a signal generator it can be of considerable help in setting and controlling levels through any amplifying chain.
Note:
Circuit From: www.redcircuits.com
[read here...]
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| Audio Peak Level Indicator Circuit |
The circuit is formed by an input buffer and ac to dc voltage converter (IC1A) feeding a window comparator (IC2A, IC2B, IC2C) which illuminates one of three LEDs at a time. No setup is required: if correct values are used for resistors R3 to R7, LED D1 will illuminate at 0dB input (0.775V RMS), LED D2 at +5dB input (1.378V RMS) and LED D3 at +10dB (2.451V RMS).
Note:
- Maximum current drawing: 12mA when one of the three LEDs is illuminated and less than 4.5mA when the input level is below 0.775V.
- LEDs of different colors can be used to mark any of the three different levels.
- Input pins of unused op-amps must be tied to negative ground. Output pins must be left open (see the upper left corner of the drawing).
R1 : 300K 1/4W Resistor
R2 : 1M2 1/4W Resistor
R3 : 510K 1/4W Resistor
R4 : 220K 1/4W Resistor
R5 : 91K 1/4W Resistor
R6 : 160K 1/4W Resistor
R7 : 56K 1/4W Resistor
R8,R9 : 100R 1/4W Resistors
R10 : 220R 1/4W Resistor
C1 : 100nF
C2 : 1µF/63V
C3 : 10µF/25V
D1,D2,D3 : LEDs (Any coloring at will)
IC1 : LM393
IC2 : LM324
IC3 : 78L05
SW1 : SPST Toggle or Slider Switch
Circuit From: www.redcircuits.com
Sunday, January 16, 2011
3 Volt LED Flasher Using 2 Transistor
Applications due to its simplicity and versatility. This Flasher circuit is great for beginners! If you build it, it will flash. And you can easily change the on-time and flash rate.
The two resistors on the base of the PNP set a threshold voltage and when power is applied the capacitor begins charging toward this voltage. When the capacitor voltage is high enough the two transistors begin to conduct. The current flow causes the voltage across the circuit to drop slightly and this drop causes a drop in the threshold voltage. The lower threshold voltage causes even more current and this positive feedback causes the circuit to rapidly turn on. It stays on until the capacitor discharges at which point a reverse process causes the circuit to suddenly switch off.
- Flashing frequency can be varied by changing R1 value in the 1M - 4M7 range.
- This circuit is very efficient when driving a small 3.2V incandescent lamp. In this case omit the LED and R3, connecting the bulb across Q2 Collector and positive supply, further reducing parts counting.
- Maximum current drawing of the bulb type used should not exceed 100mA.
- In order to facilitate oscillation when a bulb is driven, R2 value should be lowered to 82R or 68R.
R1 : 1M 1/4W Resistor R2 : 100R 1/4W Resistor R3 : 22R 1/4W Resistor C1 : 1µF/63V D1 : LED Q1 : 2N3906 PNP Transistor Q2 : 2N3904 NPN Transistor SW1 : SPST Switch B1 : 3V (Two 1.5V AA or AAA battery)
22 Watt Car Subwoofer Amplifier
This Subwoofer circuit is intended to be connected to an existing car stereo amplifier, adding the often required extra "punch" to the music by driving a subwoofer. As very low frequencies are omnidirectional, a single amplifier is necessary to drive this dedicated loudspeaker.
The power amplifier used is a BTL TDA1516BQ IC made by Philips requiring a very low parts count and capable of delivering about 22W into a 4 Ohm load at the standard car battery voltage of 14.4V.
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| 22 Watt Car Subwoofer Amplifier Circuit |
The stereo signals coming from the line outputs of the car radio amplifier are mixed at the input and, after the Level Control, the signal enters the buffer IC1A and can be phase reversed by means of SW1. This control can be useful to allow the subwoofer to be in phase with the loudspeakers of the existing car radio. Then, a 12dB/octave variable frequency Low Pass filter built around IC1B, Q1 and related components follows, allowing to adjust precisely the low pass frequency from 70 to 150Hz.
Q2, R17 and C9 form a simple dc voltage stabilizer for the input and filter circuitry, useful to avoid positive rail interaction from the power amplifier to low level sections.
List Componet Of Car Subwoofer Amplifier
List Componet Of Car Subwoofer Amplifier
P1 : 10K Potentiometer
P2 : 22K Dual Potentiometer
R1,R4 : 1K 1/4W Resistors
R2,R3,R5,R6 : 10K 1/4W Resistors
R7,R8 : 100K 1/4W Resistors
R9,R10,R13 : 47K 1/4W Resistors
R11,R12 : 15K 1/4W Resistors
R14,R15,R17 : 47K 1/4W Resistors
R16 : 6K8 1/4W Resistor
R18 : 1K5 1/4W Resistor
C1,C2,C3,C6 : 4µ7/25V
C4,C5 : 68nF Polyester Capacitors
C7 : 33nF Polyester Capacitor
C8,C9 : 220µF/25V
C10 : 470nF Polyester Capacitor
C11 : 100nF Polyester Capacitor
C12 : 2200µF/25V
D1 : LED
Q1,Q2 : BC547 NPN Transistors
IC1 : TL072 Op-Amp
IC2 : TDA1516BQ
SW1 : DPDT toggle or slide Switch
SW2 : SPST toggle or slide Switch
SPKR : 4 Ohm Woofer or two 8 Ohm Woofers wired in parallel
Circuit From: www.redcircuits.com
Car Battery Voltage Indicator
Connecting this circuit to the battery of your vehicle, you will always know at a glance the approximate voltage available. An indication of battery voltage is useful to the motorist for monitoring the battery's capacity to deliver current, and as a check on the efficiency of the dynamo or alternator.
Threshold voltages of the LEDs are set by means of two Zener Diodes (D6 & D10) plus two further Diodes wired in series (D4, D5 and D8, D9 respectively) adding a step of about 1.3V to the nominal Zener voltage.
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| Car Battery Voltage Indicator Circuit |
- Red LED (D1) is on when battery voltage is 11.5V or less.
- Amber LED (D2) is on when battery voltage is comprised in the 11.5 - 13.5V range. This indicates that the battery is good if the car is off. When car is running, this indicates no charge from dynamo or alternator.
- Green LED D7 is on when battery voltage is 13.5V or more. This indicates a normal condition when car is running and dynamo or alternator are charging.
R1,R3,R6 : 1K 1/4W Resistors
R2 : 100K 1/4W Resistor
R4,R5,R7,R8 : 3K3 1/4W Resistors
D1 : Red LED
D2 : Amber LED
D3,D4,D5 : 1N4148 150mA Diodes
D6 : BZX79C10 10V 500mW Zener Diode
D7 : Green LED
D8,D9 : 1N4148 150mA Diodes
D10 : BZX79C12 12V 500mW Zener Diode
Q1,Q2 : BC547 NPN Transistors
Q3 : BC557 PNP Transistor
Circuit From: www.redcircuits.com
18 Watt RMS Amplifier Using TIP41|42
This amplifier Circuit has output 18 Watt RMS into 8 Ohm and Frequency response 30Hz to 20KHz. It’s simple to build and you don’t need preamplifier. Besides that this Amplifier Circuit is also directly connected to Can some CD players, tuners and recorders tape. Do not exceed 23 + 23V supply. Of Q3 and Q4 must be mounted on heatsink. D1 must be in thermal contact with the Q1. Quiescent current (best measured with an Avo-meter in series with Q3 Emitter), is not critical. Adjust R3 to read a current Between 20 to 30 mA with no input signal.
List Component:
P1 : 2K Log. Potentiometer (Dual-gang for stereo) R1 : 1K 1/4W Resistor R2 : 4K7 1/4W Resistor R3 : 100R 1/4W Resistor R4 : 4K7 1/4W Resistor R5 : 82K 1/4W Resistor R6 : 10R 1/2W Resistor R7 : R22 4W Resistor (wirewound) R8 : 1K Trimmer Cermet (optional) C1 : 470nF Polyester Capacitor C2,C5 : 100µF/3V Tantalum bead Capacitors C3,C4 : 470µF/25V Electrolytic Capacitors C6 : 100nF Polyester Capacitor D1 : 1N4148 150mA Diode IC1 : TLE2141C Op-amp Q1 : BC182 NPN Transistor Q2 : BC212 PNP Transistor Q3 : TIP42A PNP Transistor Q4 : TIP41A NPN Transistor
IRF9530|IRF530 Simple MosFet Amplifier
This mosFet amplifier circuit was a sort of challenge: designing an audio amplifier capable of delivering a decent output power with a minimum parts count, without sacrificing quality.
The Power Amplifier section employs only three transistors and a handful of resistors and capacitors in a shunt feedback configuration but can deliver more than 18W into 8 Ohm with <0.08% THD @ 1KHz at the onset of clipping (0.04% @ 1W - 1KHz and 0.02% @ 1W - 10KHz) and up to 30W into a 4 Ohm load.
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| IRF9530|IRF530 Simple MosFet Amplifier Circuit |
List Component
R1 : 2K2
R2 : 27K
R3,R4 : 2K2 1/2W Trimmers Cermet or Carbon (or 2K)
R5 : 100R
R6 : 1K
R7,R8 : 330R
C1 : 22µF/25V
C2 : 47pF
C3,C4 : 100µF/50V
C5 : 2200µF/ 50V
Q1 : BC550C
Q2 : IRF530
Q3 : IRF9530
Setting up the Power Amplifier:
- Connect the Power Supply Unit (previously tested separately) to the Power Amplifier but not the Preamp: the input of the Power Amplifier must be left open.
- Rotate the cursor of R4 fully towards Q1 Collector.
- Set the cursor of R3 to about the middle of its travel.
- Connect a suitable loudspeaker or a 8 Ohm 20W resistor to the amplifier output.
- Connect a Multimeter, set to measure about 50V fsd, across the positive end of C5 and the negative ground.
- Switch on the supply and rotate R3 very slowly in order to read about 23V on the Multimeter display.
- Switch off the supply, disconnect the Multimeter and reconnect it, set to measure at least 1Amp fsd, in series to the positive supply (the possible use of a second Multimeter in this place will be very welcomed).
- Switch on the supply and rotate R4 very slowly until a reading of about 120mA is displayed.
- Check again the voltage at the positive end of C5 and readjust R3 if necessary.
- If R3 was readjusted, R4 will surely require some readjustment.
- Wait about 15 minutes, watch if the current is varying and readjust if necessary.
- Please note that R3 and R4 are very sensitive: very small movements will cause rather high voltage or current variations, so be careful.
- Those lucky enough to reach an oscilloscope and a 1KHz sine wave generator, can drive the amplifier to the maximum output power and adjust R3 in order to obtain a symmetrical clipping of the sine wave displayed.
Circuit From: www.redcircuits.com
70 Watt Guitar Amplifier Using 2N30055/MJ2955 Transistor
The Guitar power amplifier circuit of this design adopts the still new but already successful 45 Watt Class B Amplifier Simplicity and ease of construction of this amplifier, combined with the complete absence of manual settings make it ideal for Guitar or Bass amplifier.
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| 70 Watt Guitar Amplifier Circuit |
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Preamplifier + Tone Control For Guitar Amplifier Circui |
The preamplifier features two almost identical three-transistor gain-blocks based on a complementary two-stage circuit with dynamic active load of the output transistor. A circuit topology early used in Revox tape recorders and audio preamplifiers with single rail supplies in the 18 - 24Vdc range.
In this preamp the gain blocks are powered by split supplies of ±24V with two advantages: a high output voltage of about 15V RMS allowing a very wide overload margin and the facility to easily derive the preamp power supply from the power amplifier main supply.
A three-band stacked-type tone control is implemented in the second stage but, unlike the more common passive controls, active controls are used here, allowing better signal to noise ratio and overload margin with no gain loss.
List Componet Of Guitar Amplifier
R1 : 8K R2 : 3K9 R3,R6 : 1K R4 : 2K2 R5 : 15K R7 : 22K R8 : 330R R9,R10 : 10R R11,R12 : 47R R13 : 10R C1 : 1µF/63V C2 : 470pF/63V C3 : 47µF/25V C4 : 15pF/63V C5 : 220nF/100V C6 : 100nF/63V D1,D2,D3,D4 : 1N4148 150mA Diodes Q1,Q2 : BC560C PNP Transistors Q3 : Q4BC556 PNP Transistors Q5 : BC546 NPN Transistor Q6 : BD139 NPN Transistor Q7 : BD140 PNP Transistor Q8 : MJ2955 PNP Transistor Q9 : 2N3055 NPN Transistor
List Componet Of Preamplifier
P1 : 10K Potentiometer P2,P3,P4 : 47K Potentiometers P5 : 10K Potentiometer R1,R2 : 33K R3 : 220K R4 : 390R R5,R14 : 3K9 R6,R15 : 8K2 R7,R16 : 12K R8,R11,R17,R20 : 560R R9,R18 : 5K6 R10,R19 : 100R R12 : 3K3 R13 : 18K C1,C12 : 220nF Polyester Capacitors C2,C13 : 100pF Ceramic Capacitors C3,C14 : 10pF Ceramic Capacitors C4,C15 : 47µF/25V Electrolytic Capacitors C5,C16 : 100µF/25V Electrolytic Capacitors C6,C7 : 10µF/25V Electrolytic Capacitors C8,C11 : 4n7 Polyester Capacitors C9 : 10nF Polyester Capacitor C10 : 47nF Polyester Capacitor Q1 : BC560C PNP Transistor Q2,Q3,Q5,Q6 : BC546 NPN Transistors Q4 : BC557 PNP Transistor
Circuit From: http://www.redcircuits.com/
Thursday, January 13, 2011
18W Guitar Amplifier Using Darlington Transistor
The aim of this design is to reproduce a Combo amplifier of the type very common in the 'sixties and the 'seventies of the past century. It is well suited as a guitar amplifier but it will do a good job with any kind of electronic musical instrument or microphone. 5W power output was a common feature of these widespread devices due to the general adoption of a class A single-tube output stage (see the Vox AC-4 model). Furthermore, nowadays we can do without the old-fashioned Vib-Trem feature frequently included in those designs. The present circuit can deliver 10W of output power when driving an 8 Ohm load, or about 18W @ 4 Ohm. It also features a two-FET preamplifier, two inputs with different sensitivity, a treble-cut control and an optional switch allowing overdrive or powerful treble-enhancement.
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| 18W Guitar Amplifier Using Darlington Transistor Circuit |
- SW1 and related capacitors C4 & C5 are optional.
- When SW1 slider is connected to C5 the overdrive feature is enabled.
- When SW1 slider is connected to C4 the treble-enhancer is enabled.
- C4 value can be varied from 100nF to 470nF to suit your treble-enhancement needs.
- To set quiescent current, remove temporarily the Fuse F1 and insert the probes of an Avo-meter in the two leads of the fuse holder.
- Set the volume control to the minimum and Trimmer R9 to its minimum resistance.
- Power-on the circuit and adjust R9 to read a current drawing of about 25 to 30mA.
- Wait about 15 minutes, watch if the current is varying and readjust if necessary.
List Component:
P1 : 4K7 Linear Potentiometer
P2 : 10K Log. Potentiometer
R1,R2 : 68K 1/4W Resistors
R3 : 220K 1/4W Resistor
R4,R6,R11 : 4K7 1/4W Resistors
R5 : 27K 1/4W Resistor
R7 : 1K 1/4W Resistor
R8 : 3K3 1/2W Resistor
R9 : 2K 1/2W Trimmer Cermet
R10 : 470R 1/4W Resistor
R12 : 1K5 1/4W Resistor
R13 : 470K 1/4W Resistor
R14 : 33K 1/4W Resistor
C1 : 100pF Ceramic Capacitor
C2 : 100nF Polyester Capacitor
C3 : 470µF Electrolytic Capacitor
C4 : 220nF Polyester Capacitor (Optional, see Notes)
C5 : 47µF/25V Electrolytic Capacitor (Optional, see Notes)
C6 : 1µF/63V Polyester Capacitor
C7,C8,C9,C10 : 47µF/25V Electrolytic Capacitors
C11 : 47pF/63V Ceramic Capacitor
C12 : 1000µF/35V Electrolytic Capacitor
C13 : 2200µF/35V Electrolytic Capacitor
D1 : 5mm. Red LED
D2,D3 : 1N4004/400V 1A Diodes
Q1,Q2 : 2N3819 General-purpose N-Channel FETs
Q3 : BC182 NPN Transistor
Q4 : BD135 NPN Transistor (See Notes)
Q5 : BDX53A NPN Darlington Transistor
Q6 : BDX54A PNP Darlington Transistor
SW1 : pole 3 ways rotary switch
SW2 : SPST Mains switch
F1 : 1.6A Fuse with socket
T1 : 220V Primary, 48V Center-tapped Secondary 20 to 30VA Mains transformer
Wednesday, January 12, 2011
Simple FET Audio Mixer
This simple circuit mixes two or more channels into one channel (eg. stereo into mono). The circuit can mix as many or as few channels as you like and consumes very little power. The mixer is shown with two inputs, but you can add as many as you want by just duplicating the "sections" which are clearly visible on the schematic.
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| Simple FET Audio Mixer |
Note:
- As many or as few channels as are required can be added to the mixer. Do this by just duplicating the input "sections" which are clearly shown on the schematic. One version of this mixer I saw had 25 inputs!
- A shielded case is probably needed to reduce hum and help stop oscillations.
- The circuit can be powered by a single 9 volt battery.
List Component
R1, R3 : 10K Pot
R2, R4 : 100K 1/4 W Resistor
R5 : 6.8K 1/4 W Resistor
C1, C2, C3 : 0.1uF Capacitor
Q1 : 2N3819 Junction FET
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