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LM1036 – Dual DC Operated Tone/Volume/Balance Circuit

The LM1036 is an excellent choice for those that need an affordable and easy-to-assemble stereo control circuit. Also, it’s easy to use and has a lot of flexibility that allows for additional functions such as loudness control. 

If you’re working on an audio control project, we’ll guide you through your LM1036 project. 

What is LM1036?

Bass and treble control

Fig 1: Bass and treble control

The LM1036 is a DC-controlled stereo tone, volume, and balancing circuit for automobile radio, TV, and audio systems. An extra control input enables loudness compensation to be easily accomplished. 

Additionally, four control inputs determine the balance, treble, volume, and bass functions using DC voltages from a remote control system. Alternatively, you can achieve the control using four potentiometers biased from a Zener-controlled supply provided on the circuit.  

A single capacitor picked to give the desired characteristic defines each tone response.

 LM1036 Pinout

Fig 2: LM1036 pinout

LM1036 Features

  • First, it has a broad supply voltage range from 9V to 16V.
  • Second, it has a tone control, ±15 dB typical.
  • Third, it has a channel separation and big volume control range, 75 dB typical.
  • Fourth, it has low distortion, 0.06%, typical for a 0.3 Vrms input level.
  • Fifth, the LM1036 has a high signal-to-noise ratio, 80 dB, typical for a 0.3 Vrms input level.
  • Finally, it requires fewer external components.

LM1036 Circuit Application

In this section, we’re looking at the working of the LM1036. As shown below, you can see that the circuit has many details, and we’ll go through them bit by bit. 

LM1035/LM1036 working circuit

Fig 3: LM1035/LM1036 working circuit

And we’re starting with low-power audio signals, like the tuners, being fed through the circuit’s inputs. The low-strength signs get through coupling capacitor C1/C4 through R1 or R9 to the input pin of Q1/Q2. The coupling capacitor, resistors, and transistor network work as a simple preamplifier circuit to increase the signal strength. 

Preamplifier

First, capacitors C2 and C5 reduce transients, and resistors R2-R7 (R9-R15) bias the signal for Q1 and Q2, respectively. Afterward, the signal gets out through pins C and R8 (R16). 

The signal then gets through coupling capacitor C3 (C6) to IC1’s input pin 19 (2). Everything else beyond the coupling capacitor is handled by IC1. 

Tone control

Tone control circuit 

Fig 3: Tone control circuit 

Below is a circuit diagram depicting the tone control section and components. 

Here, VR1 is for controlling the volume, VR2 and VR3 are for cutting bass and treble, and VR4 adjusts balance. The stated potentiometers don’t pass audio signals but control the decrease and increase of DC or divider voltage. The DC voltage then controls pins such as IC1’s pin 17, which gives a constant control voltage of 5.4V. 

Moreover, the 5.4V controls the bass signal using VR2, and you can adjust it up and down. At the potentiometer, VR2’s middle pin is where you’ll get voltage through R17. 

In effect, it limits the current level to the bass controller pin. Furthermore, balance control, treble control, and volume control work in the same manner. 

Conclusion

In conclusion, the LM1036 is one of the cheapest and most simple audio controls you can find. Additionally, it is robust, has low power consumption, and has a wide range of applications. You can use it as shown in the sections above and reach out to us for any clarification.

Hommer Zhao
Hi, I am Hommer, the founder of WellPCB. So far, we have more than 4,000 customers worldwide. If you have any questions, you can feel free to contact me. I really appreciate any help you can provide.

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