File:3-3.5 kHz tone generator for arduino-based wow-flutter meter.png
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3-3.5 kHz tone generator for arduino-based wow-flutter meter
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| Description |
English: 3-3.5 kHz tone generator for arduino-based wow-flutter meter powered from two lithium cells (7.5...8.5V). The arduino's own timers are busy with processing input signal, so the use of PWM output (while far more stable in frequency and level) was undesirable. The circuit is the well-known function generator schematic (figure 15 in ONSemi's datasheet for LM258). Analogue "sine-like" output is taken from triangle wave node and then dropped to 1V peak-to-peak by diodes D1, D2. The logic output (top right corner) is optional. One digital arduino pin used for on/off control by way of setting artificial "ground" of the oscillator. In on-state it should be somewhat less than half of power supply, around 3.5 V.
Warning. The market is flooded with counterfeit substandard LM258/358 - these have abnormally low supply current draw, lesser unity-gain frequency and lesser slew rate than the real thing (itself very slow). The Rs and Cs in this schematic are for the genuine LM258/358. A slow fake will work, too, but the value of CT must be decreased - in my case, to 1600pF. The slew rate of the logic-level output, around 0.1V/us, may be too slow for a microcontroller interface. Русский: Генератор тестового сигнала частотой 3...3.5 кГц (стандартная установка - 3.15 кГц) для измерителя детонации на базе пятивольтового ардуино. Батарейное питание от двух литиевых элементов (7.5...8.5В). Так как собственные таймеры микроконтроллера заняты в обработке входного сигнала, использование ШИМ-выхода было нежелательно. Использована типовая схема функционального генератора. Основной (аналоговый) выходной сигнал снимается с ОУ, вырабатывающего треугольный сигнал (правая по схеме секция), и обрезается до размаха в 1В (пик-пик) диодным ограничителем. Генератор включается подачей логической единицы на управляющий вход, который задаёт внутренний уровень "средней точки" для ОУ. Его величина во включенном режиме должная быть чуть меньше половины напряжения питания ОУ, порядка 3.5 В при питании от восьмивольтовой литиевой батареи. Внимание. На рынке много левых LM258/358, с аномально низким током потребления и соответственно худшими частотой единичного усиления и скоростью нарастания (хотя куда уж хуже). С таким левочипами схема работоспособна, но емкость СТ следует уменьшить опытным путем (в моем случае хватило 1600 пФ), а фронты "импульсного" выхода могут быть неприемлемо медленными для связки с микроконтроллером. |
| Date | |
| Source | Own work |
| Author | Retired electrician |
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
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| current | 18:25, 18 May 2023 | | 1,736 × 1,024 (146 KB) | Retired electrician (talk | contribs) | upd |
| 10:50, 18 May 2023 |  | 1,732 × 1,030 (146 KB) | Retired electrician (talk | contribs) | {{Information |Description= |Source= |Date= |Author= |Permission= |other_versions= }} | |
| 10:46, 18 May 2023 |  | 1,678 × 922 (129 KB) | Retired electrician (talk | contribs) | upd | |
| 08:06, 18 May 2023 |  | 1,657 × 907 (123 KB) | Retired electrician (talk | contribs) | Uploaded own work with UploadWizard |
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