RK RKAmp2 User manual

RKAmp2 2.5+2.5W Audio Amplifier Component List and Instructions
The RKAmp2 stereo amplifier PCB has been designed around the TEA2025B 2 x 2.5 Watt stereo
amplifier I.C.
The sound signal is inputted into the circuit via a 3.5mm stereo socket
The amplifier has 2 channels of up to 2.5 Watts per channel
Produces a very high quality sound output
The PCB includes a power switch
The PCB includes a power LED
The PCB uses terminal blocks
Battery powered between 4.5V and 12V
Power is inputted to the PCB via a terminal block or jack socket
Compact design
Low cost
The PCB is a high quality double sided black PCB
A large ground plane is used to aid with dissipating heat
Component List
C1 –1000uF 16VDC electrolytic radial capacitor
C2 –100nF capacitor (tall green capacitor marked 104, non-polarised)
C3 ~ C7 –100uF 16VDC electrolytic radial capacitor
C8, C9 –470uF 16VDC electrolytic radial capacitor
C10, C11 –100nF capacitor (tall green capacitor marked 104, non-polarised)
C12, C13 –10nF capacitor (small cream box capacitors, non-polarised)
C14, C15 –2.2uF electrolytic capacitor
D1, D2 –1N4001
D3 –LED, green 3mm
IC1 –TEA2025B stereo amplifier I.C.
J1 –PCB mount 3.5mm stereo connector
J2 –2.1mm DC socket
J3 ~ J5 (PWR, LEFT & RIGHT)–2 way 5mm terminal blocks
R1 –1k (brown black red)
R2, R3 –330R (orange orange brown)
R4, R5 –1R (brown black gold)
R6, R7 –1k (brown black red)
R8, R9 –10k (brown black orange)
R10, R11 –3k3 (orange orange red)
SW1 –ultra miniature slide switch

Construction of circuit
You will need to collect the following equipment before you start soldering your circuit:
Soldering iron and stand
Solder wire
Side cutters
Pliers
Procedure for construction
1. Solder the resistors into your PCB. Take care to insert the correct resistor into the correct
place by checking the coloured bands
2. Solder the diodes in place. Ensure that the silver band on the diode aligns with the markings
on the PCB
3. Solder the power switch in place
4. Solder the stereo socket in place
5. Solder the TEA2025B in place. Ensure that the notch in the chip aligns with the notch on the
PCB. Be careful because the legs are close together - make sure you don’t connect the legs
together with solder bridges as this will stop the circuit working. An I.C. socket is not used as
the PCB acts as a heat sink.
6. Solder the LED in place. Ensure that the longer leg aligns with the + on the PCB
7. Solder the terminal blocks in place ensuring that the holes for the wires face outward
8. Solder the DC power socket in place
9. Solder the non-polarised capacitors in place
10. Solder the electrolytic capacitors in place. Be careful to ensure the longer legs are inserted
into ‘+ve’ hole.
Speakers
The PCB has been designed to power 2 full range speakers. If you have chosen a kit that is not
supplied with speakers, you will need to add your own. These should have either a 4 or 8Ω
impedance and the power rating should be equal to or greater than the maximum power output of
the amplifier.
If you are using a kit which has speakers supplied, you will need to solder the speaker cable to the
speakers.
1. Cut the speaker cable into 2 equal lengths
2. Peel the two halves of the speaker cable apart about 25mm at each end (see diagram)
3. Strip about 5mm of insulation from the ends. Twist the strands of each loose end to keep
them tidy and then tin the wires
4. For each speaker, solder the side wire with the black stripe to the + speaker terminal and the
plain side of the wire
Connecting Speaker Outputs
1. Take the first speaker and connect the wire with the black strip into the +VE side of the
terminal block marked LEFT

2. Now connect the plain wire of the speaker to the side marked –VE
3. Repeat this for the other speaker using the terminal block marked RIGHT
Connecting the PCB to a Music Device
This PCB has been designed for use with music players such as MP3 players, mobile phones with
music players and ipods. The unit is connected to a music player via the 3.5mm stereo lead with one
end inserted into the headphone socket of your music player and the other end inserted into the
PCBs 3.5mm stereo socket.
Connecting Power
The unit can be battery powered or DC PSU powered. The power is connected using the terminal
block marked J3 or via the DC socket. When using the supplied battery pack and battery snap,
connect the black wire to the 0V side and the red wire to the +VE side of the terminal block.
When using a DC PSU, 6V to 12VDC is recommended.
When the PCB is correctly powered and the switch is on, the green 3mm LED will light up.
Testing the Amplifier
PLEASE ONLY TEST THE UNIT WHEN YOU ARE SURE THE PCB IS CORRECTLY ASSEMBLED.
When the PCB has been constructed, the speakers have been attached, a music player has been
connected and power has been applied the unit is ready to be tested. Ensure the amplifier is
switched off.
Set the volume of your music player to its lowest level and press play. Switch the amplifier on and
gradually increase the volume until it can be heard. The volume is not controlled by the PCB, the
volume level will be controlled by the music player itself.