Showing posts with label portable. Show all posts
Showing posts with label portable. Show all posts
Thursday, October 16, 2014
Build a Portable GSM900 Cellular Phone Jammer Circuit Diagram
Portable GSM900 Cellular Phone Jammer Circuit Diagram Emits a carrier that sweeps the 925-960 MHz cellular tower transmitter band (handset receive band)
GSM900 Cellular Phone Jammer Circuit Diagram
Friday, September 5, 2014
New 4 Channel Portable Audio Mixer
The target of this project was the design of a small portable mixer supplied by a 9V PP3 battery, keeping high quality performance. The mixer is formed assembling three main modules that can be varied in number and/or disposition to suit everyone needs. The three main modules are:
Input Amplifier Module: a low noise schema equipped with a variable voltage-gain (10 - 100) preset, primarily intended as high quality microphone input, also suitable for low-level line input.
Tone Control Module: a three-band (Bass, Middle, Treble) tone control schema providing unity-gain when its controls are set to flat frequency response. It can be inserted after one or more Input Amplifier Modules and/or after the Main Mixer Amplifiers.
Main Mixer Amplifier Module: a stereo schema incorporating two virtual-earth mixers and showing the connection of one Main Fader and one Pan-Pot.
The image below shows a Block diagram of the entire mixer featuring four Input Amplifier Modules followed by four in-out switchable Tone Control Modules, one stereo Line input, four mono Main Faders, one stereo dual-ganged Main Fader, four Pan-Pots, a stereo Main Mixer Amplifier Module and two further Tone Control Modules switchable in and out for each channel, inserted before the main Left and Right outputs.
Obviously this layout can be rearranged at everyone wish. An astonishing feature of this design lies in the fact that a complete stereo mixer as shown below in the Block diagram draws less than 6mA current!
Block diagram:
Input Amplifier Module
Parts:
R1 = 22K - 1/4W Resistor
R2 = 22K - 1/4W Resistor
R3 = 47K - 1/4W Resistor
R4 = 47K - 1/4W Resistor
R5 = 47K - 1/4W Resistor
R6 = 4K7 - 1/4W Resistor
R7 = 22K - 1/4W Resistor
R8 = 220R - 1/4W Resistor
R9 = 2K - 1/2W Trimmer Cermet (See Notes)
R10 = 470K - 1/4W Resistor
R11 = 560R - 1/4W Resistor
R12 = 100K - 1/4W Resistor
R13 = 220R - 1/4W Resistor
C1 = 470nF - 63V Polyester Capacitor
C2 = 100µF - 25V Electrolytic Capacitor
C3 = 2µ2 - 63V Electrolytic Capacitor
C4 = 2µ2 - 63V Electrolytic Capacitor
C5 = 2µ2 - 63V Electrolytic Capacitor
C6 = 47pF - 63V Ceramic Capacitor
C7 = 4µ7 - 63V Electrolytic Capacitor
C8 = 100µF - 25V Electrolytic Capacitor
Q1 = BC560C - 45V 100mA Low noise High gain PNP Transistor
Q2 = BC550C - 45V 100mA Low noise High gain NPN Transistor
IC1 = TL061 - Low current BIFET Op-Amp
Circuit Description:
The basic arrangement of this schema is derived from the old Quad magnetic pick-up cartridge module. The schema was rearranged to cope with microphone input and a single-rail low voltage supply. This low-noise, fully symmetrical, two-transistor head amplifier layout, allows the use of a normal FET input Op-Amp as the second gain stage, even for very sensitive microphone inputs. The voltage-gain of this amplifier can be varied by means of R9 from 10 to 100, i.e. 20 to 40dB.
Notes:
- R9 can be a trimmer, a linear potentiometer or a fixed-value resistor at will.
- When voltage-gain is set to 10, the amplifier can cope with 800mV peak-to-peak maximum Line levels.
- Current drawing for one Input Amplifier Module is 600µA.
- Frequency response is 20Hz to 20KHz - 0.5dB.
- Total Harmonic Distortion measured with voltage-gain set to 100: 2V RMS output = <0.02%>
- Total Harmonic Distortion measured with voltage-gain set to 10 & 33: 2V RMS output = <0.02%>
- THD is much lower @ 1V RMS output.
- Maximum undistorted output voltage: 2.8V RMS.
Wednesday, August 20, 2014
Portable 9v Headphone Amplifier
After several requests by correspondents, the decision of designing a 9V powered Headphone Amplifier was finally taken. The main requirement was to power the schema by means of a common, PP3 (transistor radio) alkaline battery. So, implementing a low current drawing schema was absolutely necessary, though preserving a High Quality performance.
Parts:
P1 = 22K
R1 = 18K
R2 = 68K
R3 = 68K
R4 = 68K
R5 = 18K
R6 = 68K
C1 = 4.7uF-25v
C2 = 4.7uF-25v
C3 = 22pF
C4 = 220uF-25v
C5 = 220uF-25v
C6 = 4.7uF-25v
C7 = 22pF
C8 = 220uF-25v
J1 = 3.5mm Stereo Jack
B1 = 9V Alkaline Battery
IC1 = NE5532-34
SW1 = SPST Toggle Switch
* The appearance of the 5534 low-noise op-amp at a reasonable price was much appreciated by audio designers. It is now difficult or impossible to design a discrete stage that has the performance of the 5534 without quite unacceptable complexity.
* 5534 op-amps are now available from several sources, in a conventional 8-pin d.i.l. format. This version is internally compensated for gains of three or more, but requires a small external capacitor (5-15pF) for unity-gain stability. The 5532 is a very convenient package of two 5534s in one 8-pin devices with internal unity-gain compensation, as there are no spare pins.
* The 5534/2 is a low-distortion, low-noise device, having also the ability to drive low-impedance loads to a full voltage swing while maintaining low distortion. Furthermore, it is fully output short-schema proof. Therefore, this schema was implemented with a single 5532 chip forming a pair of stereo, inverting amplifiers, having an ac gain of about 3.5 and capable of delivering up to 3.6V peak-to-peak into a 32 Ohm load (corresponding to 50mW RMS) at less than 0.025% total harmonic distortion (1kHz & 10kHz).
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