Hello everyone, good to see you back here. Today in this tutorial we are going to make a preamp circuit without using any kind of transistor or ic. This preamplifier circuit will able to control and adjust Bass, Treble and volume manually.
In this tutorial we are making two preamplifier (Bass, treble and volume control) circuits.I will demonstrate you how both the circuits and different from each other. In the section a youtube video is embedded so that we can easily compare both the circuits.
Preamplifier:
This is a
complex circuit which is used to modify the sound signal before giving it to
main power amplifier. Because sound signal consists a lot of up-down frequency
curves. For Bass we need low frequency signal instead of high, so high
frequency is cut-off by the circuit. Similarly in treble we need high frequency
for better response. That’s why we are designing a preamp to make the overall
signal (bass-treble and volume) adjustable.
This is the prototype PCB for the same circuit.
Circuit components:
For mono-amplifier board:
- 4pcs 100nf polyester film capacitor
- 2pcs 1k 0.25-ohm resistor
- 3pcs potentiometers (signal channel)
For stereo-amplifier board:
- 8pcs 100nf polyester film capacitor
- 4pcs 1k 0.25-ohm resistor
- 3pcs potentiometers (stereo-double channel)
Circuit diagram:
Gerber files:
Circuit description:
Here we are
using three potentiometers (two of 100k and one of 50k). by 100k potentiometers
we can adjust Bass and Treble. Volume level can be controlled using 50k
potentiometer. In this circuit we will only use passive components that’s why
project become much simpler.
Polyester
film 100nF capacitors and 1kohm 0.25 watts resistors are used in this circuit.
We can choose some close values to them.
To make
this circuit compatible to stereo amplifier we have to use stereo double
potentiometers and all the components are doubled then.
Result:
After
reviewing this circuit and making some noise with this, everything is going
fine but passive components are not able to cut the frequency curve as desired
so I changed my mind and then go for prototype PCB.
*The above
circuit is very good and will be work fine, for more follow the next circuit.
For that I
discover some circuits on internet then make the schematics accordingly. This
time we sent our files to NextPCB to get best prototype board.
Try PCB making software NextDFM from here.
Gerber
files:
Circuit components:
- Potentiometer (100k,50k)
- Capacitors (4.7uf, 220uf)
- Bc548 transistor
- Resistors (150k,100k, 47k,10k,6.8k, 1k)
- Polyester film capacitors (220pf, 100nf,47nf)
- Screw terminal
Circuit description:
this is a stereo preamplifier circuit and through this we can
control bass, treble and volume of the sound signal in a very professional way.
This circuit has good frequency response. All the components used here are
easily available in online or offline market. This circuit basically follows
the same phenomena as above one but one step modified. To power up the transistor
circuit we have to supply +12 volt to this circuit.
Result:
Overall
sound control is good, there is no any type of humming. For more better response,
we can use high quality capacitors and resistors.
For more
circuits and detailed description follow us on Instagram page. This circuit can me modified more for best results till then stay tuned with us.
PCB designs and making:
We can make
pcb at home or we can use breadboard to develop this circuit but for better
performance and simplicity we made a circuit using Nextdfm and then order the
PCB from Nextpcb.
I made some
changes in the PCB circuit, originally it was made by electro India so all
credit goes to him.
2 Comments
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