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To favoritesThe tone and volume control unit is intended for use both as part of the amateur radio construction kit “Low Frequency Amplifier” (set NM2012), and for independent construction of low-frequency amplifying devices.
Specifications
Peculiarities
- The tone is adjustable at frequencies of 40 Hz and 16 kHz.
- Tone control depth – 17 dB
- Balance adjustment - 10 dB
- Volume adjustment – from +20 dB to -70 dB
Principle of operation
The circuit is made on the TDA1524 integrated circuit. For adjustments, paired variable resistors with a nominal value of 2x100 kOhm are used, the sections of which are connected in parallel. This ensures higher mechanical strength of the resistor installation and, in most cases, eliminates the need for additional board fastening. Thus, the module can be held in the amplifier housing only by attaching variable resistors.
Device design
All components included in the kit are installed on a printed circuit board by soldering.
Scheme
Contents of delivery
- Printed circuit board - 1 pc.
- Set of components - 1 pc.
- Instructions - 1 pc.
What is required for assembly
- For assembly you will need: wire, soldering iron, side cutters.
Assembly order
- Observe the following requirements:
- When installing fixed resistors, check their value using a multimeter.
- When installing transistors and diodes, be careful they have polarity.
- When installing, use only inactive flux.
- Before switching on for the first time, check the installation for any short circuits in the tracks.
- When installed correctly, the device starts working immediately and does not require configuration.
Preparation for use
- Examination:
- Using shielded wire, connect the module, pins 3 and 4, to the input of the stereo amplifier.
- Set all variable resistors to the middle position.
- Apply 12V power to pins 5 and 6, observing the polarity.
- Touch contacts 1 and 2 with your finger. At the same time, a light background should be heard in the speaker.
- Connect the MP3 player and rotate the variable resistors to check the tone control.
- Check completed. Enjoy your use.
terms of Use
- Temperature -30C to +50C.
- Relative humidity 20-80% without condensation.
Precautionary measures
- Do not exceed the maximum permissible supply voltage of the module.
- Do not confuse the polarity of the module power supply.
- Failure to comply with these requirements will result in device failure.
Specifications regulator: Frequency band 20-20,000Hz Tone control at a frequency of 40Hz (bass) -19/+17db Tone control at a frequency of 16Khz (treble) -15/+15db Balance adjustment -40db Input impedance 10-60K Output impedance 300Om Volume adjustment not less than -80 /+21.5db Harmonic coefficient no more than 0.3% Relative noise level no more than -80db Supply voltage 6-18VThis circuit is implemented on an integrated circuit from Philips TDA1524A (A1524A is an analogue from RFT). The microcircuit is a two-channel (stereophonic) volume control, balance and timbre of low and high frequencies. There is also loudnes (frequency compensation). Any variable resistors can be used, because Volume, balance and timbre adjustment in this chip is carried out electronically. Substring resistors R7 and R8 regulate the gain of the output signal; button S1, which turns on the frequency compensation of the volume control (turned off in the diagram), must be latched. For those who want to constantly use frequency compensation without the possibility of turning it off, elements S1 and R9 can be excluded from the circuit. During operation, the microcircuit heats up. Glue to it (for example, with Moment glue) a small U-shaped aluminum radiator. This will increase the reliability and service life of the microcircuit.
On the printed circuit board shown here measuring 50X31 mm, in addition to the volume, balance and tone controls, there is a power amplifier described in the article Power Amplifier on the TDA1552Q. The devices are separated on the board by a red dotted line. On the left is the volume, balance and tone control on the TDA1524A, on the right is the power amplifier on the TDA1552Q. The elements of the amplifier R1 C3 are soldered on the side of the printed conductors.
List of radioelements
| Designation | Type | Denomination | Quantity | Note | Shop | My notepad |
|---|---|---|---|---|---|---|
| U1 | Two-channel volume, balance and tone control | TDA1524A | 1 | To notepad | ||
| C1, C2 | Capacitor | 68 nF | 2 | To notepad | ||
| C3, C4 | Capacitor | 15 nF | 2 | A film capacitor is desirable | To notepad | |
| C5 | 100 µF | 1 | To notepad | |||
| C6-C9 | Capacitor | 0.1 µF | 4 | A film capacitor is desirable | To notepad | |
| C10 | Electrolytic capacitor | 100 µF | 1 | To notepad | ||
| C11, C12 | Capacitor | 0.22 µF | 2 | A film capacitor is desirable | To notepad | |
| C13, C14 | Electrolytic capacitor | 2.2 µF | 2 | To notepad | ||
| C15 | Capacitor | 0.022 µF | 1 | A film capacitor is desirable | To notepad | |
| R1-R4 | Variable resistor | 47 kOhm | 4 | To notepad | ||
| R5, R6 | Resistor | 10 kOhm | 2 |
First, we cut off the required piece of PCB, sand it with scratch paper, and degrease it with acetone.
He carefully wrapped it and began to mercilessly fry the paint so that it would transfer from the paper to the PCB.
After ironing, give the board time to cool. Next, things move to the bathroom. Place the board in water to allow the paper to soften. At this time, you can drink tea or coffee - whoever prefers what.
It turned out to be a beautiful photo, didn’t it? Let's move on, after we have refreshed ourselves, we can move on to what, in my opinion, is the most painstaking task - wiping the paper off the PCB. We carefully tear off the paper so as not to tear it off along with our tracks.
All that remains, without fanaticism, we rub off with our fingertips.
Then we move on to the important matter - etching. I usually poison in ferric chloride, since it is faster than etching in copper sulfate (at first I poisoned with it, but was disappointed, because the wait reached 2 days). Carefully place the board in the solution so as not to splash it.
Now you can go for a walk, or do some other activity. An hour has passed, we can take out our board. Usually it is etched faster, but the textolite I found in the store was only 2-sided, and the solution was not the freshest. We take out the board and see our tracks.
The tracks are now under the toner, it needs to be cleaned. Many people do this with acetone or another solvent. I do this with the same fine sandpaper.
That's all, the stage of preparing the board for the tone block circuit is completed. Next it will be more interesting - we will drill holes for the parts.
There is nothing else to drill with except a drill; it is extremely inconvenient, especially since its chuck is wobbly. So don't criticize too much for crooked holes :)
We perform soldering of the tone block parts. We start doing this with the socket (connector) for the TDA1524A chip.
Now we solder all the jumpers and small parts. We insert the microcircuit last, since during soldering it can overheat and fail, which is very sad.
Well, that's basically all! Below you can see a photo of my tone block.
After soldering, we check for the absence of a short circuit, snot between the tracks, if nothing like this is noticed, then you can safely turn it on. Video demonstration of the device:
I always carry out the first start with a serial connection of a 12-volt car light bulb (for current limiting in the event of a short circuit). I assembled the tone block - everything works great. The article was written by: Evgeniy (ZhekaN96).