Schematic & Wiring Diagram

FM Receiver / TV Tuner TDA7000

This simple one chip FM receiver / TV tuner will acquiesce you to accept frequencies from 70 up to 120MHz. With this baby receiver it is accessible to auto TV stations, absolute 88 - 108MHz FM band, aircraft chat and abounding added clandestine transmissions. It is a absolute accompaniment to any FM Transmitter abnormally if FM bandage in your breadth is actual crowded. TDA7000 receiver offers actual acceptable acuteness accordingly it will alike acquiesce you to auto weaker signals that cannot be heard on accepted FM receivers.

A accurate affection of presented TDA7000 FM receiver is a voltage controlled oscillator agnate to TV tuners that are acclimated in television sets. Abundance is acquainted by capricious the ascribe voltage to the oscillator. The advantage of this blazon of oscillator is that you can use approved 100K potentiometer to absolutely tune to a accustomed broadcast. Tuning can be performed abundant quicker and absolutely than by application a trimmer (variable capacitor). Trimmers will additionally about-face the abundance as you blow them area potentiometer will not. Trimmer additionally needs to be placed on receiver's PCB to abbreviate the devious capacitance area potentiometer can be calmly placed anywhere you appetite because it will not be afflicted by any alien capacitance.

Long Range AM transmitter circuit Diagram

The ambit for a able AM transmitter application bowl resonator/filter of 3.587 MHz is presented here. Resonators/filters of added frequencies such as 5.5 MHz, 7 MHz and 10.7 MHz may additionally be used. Use of altered abundance filters/resonators will absorb agnate aberration in the amount of inductor acclimated in the catchbasin ambit of oscillator affiliated at the beneficiary of transistor T1.

The AF ascribe for accentuation is amid in alternation with emitter of transistor T1 (and resistor R4) application a transistor radio blazon audio disciplinarian agent as apparent in the circuit. Articulate RF achievement is developed beyond the catchbasin ambit which can be acquainted to resonance abundance of the filter/resonator with the advice of assemblage condenser C7. The abutting two stages formed application low-noise RF transistors BF495 are, in fact, affiliated in alongside for addition of articulate arresting accompanying from beneficiary of transistor T1 to bases of transistors T2 and T3. The accumulated achievement from collectors of T2 and T3 is fed to antenna via 100pF capacitor C4.

The ambit can be calmly accumulated on a general-purpose PCB. The ambit of the transmitter is accepted to be one to two kilometers. The ambit requires adapted 9-volt ability accumulation for its operation. Note: Dotted lined indicates added affiliation if a 3-pin clarify is acclimated in place.

4 Transistor 500mW FM Transmitter Circuit Diagram

As shown, the audio ascribe is a microphone, which uses 2 x 2N3904 as the microphone audio preamplifier. The audio/mic ascribe akin is adjustable by agency of a 5k preset / potentiometer.

The ambit uses a Colpitts oscillator for abundance generation, which is chargeless active and operates at the axiological abundance i.e. no circuitous abundance multiplication or control. The abundance affability basic of the ambit consists of 2 5pF (picoFarad) capacitors and a distinct 10uH (micro-Henry) inductor. These apparatus can be adapted if a change in abundance is appropriate - conceivably alike replaced with capricious capacitors (if you're up to the challenge).

An achievement RF amplifier takes the abundance produced by the Colpitts oscillator and amplifier to about about the 500mW (0.5 Watt) ambit - so this is the almost achievement ability of this FM transmitter. You are brash that back this transmitter operates at the axiological frequency, and because there is no achievement filter, there is acceptable to be some abundance alluvion and harmonics/spurious emissions.

Multi-Band AM DSB Transmitter Circuit Shcematic

The ambit of AM transmitter is advised to address (amplitude modulated) DSB (double ancillary band) signals. A articulate AM arresting consists of a carrier and two symetrically spaced ancillary bands. The two ancillary bands accept the aforementioned amplitude and backpack the aforementioned information. In fact, the carrier itself coveys or carries no information. In a 100% articulate AM arresting 2/3 rd of the ability is ashen in the carrier and alone 1/6th of the ability is independent in anniversary ancillary band.

In this transmitter we abolish the carrier and transmitt alone the two ancillary bands. The able achievement of the ambit is three times that of an agnate AM transmitter.

Op Amp IC741 is acclimated actuality as a microphone amplifier to amplify the articulation best up by the condenser microphone. The achievement of the op amp is fed to the bifold counterbalanced modulator (DBM) body about four IN4148 diodes. The accentuation akin can be adapted with the advice of preset VR1.

The carrier is generated application clear oscillator active about BC548 transistor T2. The carrier is added amplified by transistor T1, which additionally acts as a absorber amid carrier oscillator and the counterbalanced modulator. The alive abundance of the transmitter can be afflicted by application crystals of altered frequencies. For multi abundance operation, alternative of altered crystals can be fabricated application a selector switch.

Ths achievement of the DBM contains alone the artefact (of audio and carrier) frequencies. The DBM suppresses both the ascribe signals and produces bifold ancillary bandage suppressed carrier (DSBSC) at its output. However, back the diodes acclimated in the counterbalanced modulator are not absolutely matched, the achievement of the DBM does accommodate some balance carrier. This is accepted as carrier leakage. By adjusting the 100 ohm preset VR2 and trimmer C7 you can absent the carrier leakage.

To accept DSB signals you charge a exhausted abundance oscillator to reinsert the missing carrier. If you don't accept a exhausted abundance oscillator, or appetite to transmitt alone AM signal, acclimatize preset VR2 to aperture some carrier so that you can accept the signals on any accustomed radio receiver. In AM approach 100% accentuation can be accomplished by adjusting preset VR1 and VR2.

The DSBSC arresting accessible at the achievement of the counterbalanced modulator is amplified by two stages of RF beeline amplifiers. Transistor 2N2222A (T3) is acclimated as an RF pre amplifier, which provides abundant arresting addition to drive the final ability amplifier body about transistor SL100B. The achievement of the final ability amplifier is affiliated to the antenna.

All coils are to be anguish ferrite balun amount (same as acclimated in TV balun agent of admeasurement 1.4 cm * 0.6 cm) application 24 swg enameled chestnut wire. Proper calefaction bore should be provided for SL100B transistor acclimated as final ability amplifier.