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Circuit diagram:

Author: Peter Howarth - Copyright: Silicon Chip Electronics

Look at any good car stereo system and you’ll probably see a Pioneer car stereo unit plugged into the console. Alongside with quality speakers and a strong lineup of accessories like LCD panels and navigational devices, Pioneer products/Pioneer car stereos have earned a huge following the world over.  

The Pioneer Company is a Tokyo-based corporation, and is one of the world leaders in digital entertainment products. The Pioneer Company was first founded in 1938 in Tokyo as a small radio and speaker repair shop business but today, they are recognized as a leader in technology advancements in the consumer electronics industry.

The company is truly deserving of their name. They are respected for many innovations such as interactive cable TV, the Laser Disc player, developing the first Compact Disc player for the car and the first detachable face car stereo, DVD and DVD recording, plasma display, and organic electroluminescent display. Their strength in optical disc and display technology is complemented by its state-of-the-art software products and manufacturing capabilities.

Nowadays, Pioneer car stereo units are not just simple head units. A car stereo can easily be comprised of several items built into the console of the car. Hardware like navigational devices, DVD players with LCD panels, coupled with the standard array of compact disc, mp3 and cassette players now usually go together. One would be hard-pressed not to acquire all of these, as it is such a delight to see these units work harmoniously. But traditionally, a Pioneer car stereo unit is a head unit with a radio, cassette and cd player. No matter how bare-bones this might sound, anyone will surely be impressed with the sound quality and features a Pioneer car stereo can boot.

Something like the DEH-P90HDD Pioneer car stereo single CD player head unit. The DEH-P90HDD allows you to record CD Audio (from the unit itself or from a changer) onto a 10GB hard disc drive, which holds about 200 audio CDs (using ATRAC3 digital compression). Your CDs are recognized by the pre-installed Gracenote CDDB database, which includes auto-playlists that make finding a specific CD easy. This Pioneer car stereo unit can also play your MP3 CDs plus CD Audio, CD-RW, and CD-R discs. Also, the MagicGate Memory Stick player lets you play recorded Memory Stick tracks. The Organic EL display is easy to read and accepts image downloads, so you can customize its look. Built-in DSP offers a 13-band graphic EQ and a huge variety of tools. The DEH-P90HDD is XM Ready and provides a steering wheel remote.   

If cassettes are your thing, the KEH-P4020 Pioneer car stereo cassette player head unit is a good product to choose. It is a full logic cassette system with multi-color display, 45Wx4 High Power, EEQ™ equalizer system, Tuner, IP-Bus System Control, flap face and has a detachable face security. 

If you’re planning to buy a Pioneer car stereo unit, why not match it with a set of Pioneer speakers too? Pioneer car stereo has made another innovation in their REV Series speakers, which incorporates technological breakthroughs in their IASCA award-winning Premier Reference Series (PRS) speakers. Rev Series speakers boast Pioneer’s Kevlar Fiber Composite Cones, Soft-dome tweeters and Wave guides. Each speaker features a bright yellow cone and distinctive wave guides, plus a six-spoke grill with a titanium finish that simulates chrome wheels.

With all these impressive products, is it still a wonder why they call Pioneer car stereos “Pioneer”?

The simple telephone ring tone amplifier circuit explained in this article saves the inconvenience of picking the telephone handset while speaking over a call. This circuit also particularly becomes useful when theres a need of the conversation to become audible to a number of people or a group of people.

When the conversation needs to become public the amplifier circuit simply needs to be switched ON so that rhe on going talks becomes amplified and can be heard loud and clear.

The most impressive feature of the proposed circuit design is that it does not require a direct or physical integration with the telephone line rather everything is done quite wirelessly.

The sensing of the telephone signals is done by the pick-up coil which may be placed very close to the telephone or the telephone wire.

The telephone pickup coil is made up of about 2000 to 3000 turns of 36 SWG super enameled copper wire wound over a plastic/paper former having a diameter of 2 inches.

Since this coil becomes the sole sensing agent should be made with lot of care and concentration.

Refer circuit diagram

When placed near to the telephone wire, the signals from the wire are transferred to the coil through the principle of mutual conduction and the audio pulses which is created by talking over the telephone mic is picked by the coil and sent to the main circuit for amplification.

The amplifier unit basically consists of the IC CA 3020 which forms the heart of the circuit. It just requires a few other passive components for the IC to become fully operational as en efficient audio amplifier.

The sensed input from the coil is not more than 300 mV, but becomes quite sufficient for the IC CA3020 to process the input into an amplified version over the connected loudspeaker.



Adjustments

After you finish assembling the circuit as shown in the figure, connect the pick up coil wire across the input of the amplifier and ground via the shown pot. Use shielded wire for this otherwise many unnecessary stray inputs may get into the amplifier. The pot acts as the sensitivity control or the volume control here.

Now switch on the power to the circuit.
Next gently place the pick up coil near the wire of the handset of the landline receiver.
Now as you lift the handset, the dial tone from the telephone should be heard loud and clear over the amplifier loudspeakers.
Make a call over the phone through another phone, all the audio during the calling procedure will be picked by the telephone amplifier circuit and converted into audible signals.

You may either use a battery for operating the circuit or a simple regulated power supply may be used. Alternatively you may use  an AC DC adapter also for powering this circuit.

This is a design circuit for constant voltage constant current (CVCS) regulator doesn’t mean a system with a constant load, since there will be no regulation in such case.  What we call CVCS regulator is a regulator with two modes. This is the figure of the circuit;

The first mode is constant voltage, where the regulator trying to regulate the supply to a variable load at a constant voltage. In this mode off course the current will be variable depending on the load. The current will vary a range that is limited to a predetermined maximum current level. When the load draw more current than this level then the regulator will switch to constant current mode, where the regulator keep the current at a fixed maximum value. Any attempt of the load to draw more current will cause the regulator to decrease the voltage as a reaction to keep it constant, so it acts like a current limiter. Here is the schematic diagram of the CVCS regulator.