Eight RETRO RADIO Instructions Manual Download Page 10 | Manualshive

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Eight RETRO RADIO Instructions Manual Download Page 10

The

volume potentiometer

contains an additional switch and

thus has five connecting wires. By turning the axis to the far

left, the radio is turned off. As a special feature of this poten

-

tiometer, the resistance curve is not linear but adapted to the

human sense of hearing. Hence, the middle setting provides

significantly more than half the total resistance.

Volume potentiometer

10

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Summary of Contents for RETRO RADIO

Page 1: ......

Page 2: ...components and gradually build a complex circuit Finally use the completed FM radio to listen to your local FM station in great sound quality The FM radio is easy to assemble and yet offers many possi...

Page 3: ...troduction 2 The Components 4 Step 1 Mounting the Amplifier 11 Step 2 Sound Generator 15 Step 3 Improved Amplifier 18 Step 4 Simple Radio 21 Step 5 Tuning 24 Step 6 Mounting in the Housing 27 Troubles...

Page 4: ...are built on a bread board The centre part contains 46 contact strips with five contacts each The two long strips with 20 contacts along the edges are typically used to provide the operating voltage I...

Page 5: ...to each other The individual steps are illustrated with assembly drawings photos or circuit diagrams The symbols in the circuit diagrams are as follows FM board Capacitor E capacitor Resistor Potentio...

Page 6: ...and thus the other components It is important to supply the radio board with an operating voltage of only 3 V It must never be con nected directly to a 9 V battery Instead a voltage regulator is requ...

Page 7: ...at the top left corner Pin 4 bottom right is the negative terminal of the power supply The ampli fier operates at 9 V and provides 0 5 W to the loudspeaker The loudspeaker exhibits a resistance of 8 O...

Page 8: ...e to pay attention to the mounting direction as the e cap will be destroyed when the polarity is reversed The negative terminal is the shorter leg it is additionally marked by a white bar The kit cont...

Page 9: ...he fourth gold ring represents a tolerance of 5 The kit contains four resistors in total 100 brown black brown 1 k brown black red 10 k brown black orange 220 k red red yellow Basically a potentiomete...

Page 10: ...By turning the axis to the far left the radio is turned off As a special feature of this poten tiometer the resistance curve is not linear but adapted to the human sense of hearing Hence the middle s...

Page 11: ...th clip Strain relief 100 F e cap LM386 amplifier 1 k resistor brown black red Step 1 Mounting the Amplifier Required components Breadboard LM386 amplifier IC 100 F e capacitor 1 k resistor brown blac...

Page 12: ...me being Let s start with the first step and insert the compo nents on the breadboard as shown in the illustration Inserting components in the breadboard requires some force The connection wires thus...

Page 13: ...just fine As most of the components will remain in the same position it already makes sense to install a strain relief for the battery wires at this stage to prevent the battery clip from damage Remov...

Page 14: ...14...

Page 15: ...Step 2 Sound Generator Required components 10 k resistor brown black orange 15...

Page 16: ...f the LM386 is an inverting input When the voltage at this input increases the amplified voltage at the output decreas es In contrast pin 3 does not invert the signal any input signal is amplified at...

Page 17: ...17...

Page 18: ...Step 3 Improved Amplifier Required components 100 nF disc capacitor 100 F e capacitor hook up wire 18...

Page 19: ...radio in this place Pin 3 of the amplifier is now additionally connected to GND This reduces distortions that would otherwise occur by contact resistances on the breadboard Pin 2 of the IC is the amp...

Page 20: ...20...

Page 21: ...ep 4 Simple Radio Required components TDA7088 FM IC receiver board HT7530 voltage regulator 10 k resistors brown black orange 1 k resistor brown black red 100 resistor brown black brown hook up wire 2...

Page 22: ...attached to the positive terminal of the battery and the ground pin right to the negative terminal The output left now provides a stable voltage of 3 V Pay atten tion to the mounting direction The fl...

Page 23: ...may already be lucky and be able to receive a radio station As the tuning contacts are not yet attached you will receive a random frequency However by momentarily touching the S R and contacts on the...

Page 24: ...Step 5 Tuning Required components Hook up wire 24...

Page 25: ...ouch each other Bend the wires so that they make contact when you push them slightly Momentarily touching the push button causes the radio to search for the station of the next higher frequency After...

Page 26: ...be cut off In this way the minimum frequency of a little lower than 87 5 MHz is set The board contains an additional inte grated capacitor to hold the current tuning voltage By touching the reset push...

Page 27: ...Step 6 Mounting in the Housing Required components Volume potentiometer tuning potentiometer 220 k resistor red red yellow washers cap nuts hook up wire both rotary knobs radio housing 27...

Page 28: ...the component from twisting Slide the loudspeaker into the provided bracket You can additionally secure it with a little glue Attach the breadboard between the potentiometers and the loudspeaker At t...

Page 29: ...29...

Page 30: ...had been attached The second potentiometer will be used for scanning the frequencies When the potentiometers are attached you can close the housing and control the radio from the outside Compared to...

Page 31: ...the tuning process An improperly adjusted station will automatically be tuned more precisely While slowly scanning the FM range you will register a certain lock in range where the radio clings to a c...

Page 32: ...able to receive the more powerful stations clearly First test the radio at low or medium vol ume At full volume clipping at the amplifier might already occur and cause audible distortions Depending on...

Page 33: ...would point to an improper connection Jiggle the indi vidual wires to track down connection problems Scratching sounds that appear while you lightly touch a wire or a compo nent are caused by imprope...

Page 34: ...Its volume indicates the voltage Also test the full operating voltage 9 V very loud and the negative connection GND 0 V no sound Further tests should yield the following results BAT pin of the board 3...

Page 35: ...Measured voltages 35...

Page 36: ...its are designed to provide reasonable protection against harmful interference in a residential installation This equipment generates uses and can radiate radio frequency energy and if not installed a...

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