{"product_id":"frequency-to-voltage-converter-tachometer-variable-reluctance-magnetic-pickup-to-voltage-converter","title":"Frequency To Voltage Converter (Tachometer) – Variable Reluctance Magnetic Pickup to Voltage Converter","description":"\u003cp\u003eThe circuit shown here is a\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003efrequency-to-voltage converter\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003ethat can be used in many applications. This is a signal conditioner for\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eVariable Reluctance Magnetic Pickup Sensor\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eused in engines or machines to detect the speed by sensing gears’ teeth. The input signal level is\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003e20mV to 28V\u003c\/strong\u003e. The circuit provides 1V (67Hz\/Volt) when the input frequency is 67Hz with a 15V power supply. The maximum input frequency is\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003e1Khz\u003c\/strong\u003e. The project was built using\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eLM2907N-8\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eIC, refer to the datasheet of the chip for more information and various configurations. CN1 connector is provided to connect the sensor or input signal. D1 power LED, CN2 Power input, and Voltage output. Use the formula below to calculate voltage output from the desired frequency input.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eV\u003csub\u003eOUT\u003c\/sub\u003e\u003cspan\u003e \u003c\/span\u003e= f\u003csub\u003eIN\u003c\/sub\u003e\u003cspan\u003e \u003c\/span\u003e× VCC × R3 × C4\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe\u003cstrong\u003e\u003cspan\u003e \u003c\/span\u003eLM2907\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eseries of tachometer circuits are designed for minimum external part count applications and maximum versatility. To fully exploit its features and advantages, first examine its theory of operation. The first stage of the operation is a differential amplifier driving a positive feedback flip-flop circuit. The input threshold voltage is the amount of differential input voltage at which the output of this stage changes state. Two options (8-pin LM2907 and LM2917) have one input internally grounded so that an input signal must swing above and below ground and exceed the input thresholds to produce an output. This is offered specifically for magnetic variable reluctance pickups which typically provide a single-ended AC output. This single input is also fully protected against voltage swings to ±28 V, which are easily attained with these types of pickups. The differential input options (LM2907, LM2917) give the user the option of setting his input switching level and still having the hysteresis around that level for excellent noise rejection in any application. Of course, to allow the inputs to attain common-mode voltages above ground, input protection is removed and neither input should be taken outside the limits of the supply voltage being used. It is very important that an input not go below ground without some resistance in its lead to limit the current that will then flow in the epi-substrate diode. Following the input stage is the charge pump where the input frequency is converted to a DC voltage. To do this requires one timing capacitor, one output resistor, and an integrating or filter capacitor. When the input stage changes state (due to a suitable zero crossing or differential voltage on the input) the timing capacitor is either charged or discharged linearly between two voltages whose difference is VCC\/2. Then in one-half cycle of the input frequency or a time equal to 1\/2 fIN the change in charge on the timing capacitor is equal to VCC\/2 × C1.\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eOperating Supply 15V DC\u003c\/li\u003e\n\u003cli\u003eOutput 67Hz\/Volt (67Hz = 1Volt)\u003c\/li\u003e\n\u003cli\u003eMaximum input Frequency 1Khz\u003c\/li\u003e\n\u003cli\u003eGround Referenced Tachometer Input Interfaces Directly with Variable Reluctance Magnetic Pickups\u003c\/li\u003e\n\u003cli\u003eGround-Referenced Tachometer is Fully Protected from Damage Due to Swings Above VCC and Below Ground\u003c\/li\u003e\n\u003cli\u003eOutput Swings to Ground for Zero Frequency Input\u003c\/li\u003e\n\u003cli\u003eFrequency Doubling for Low Ripple\u003c\/li\u003e\n\u003cli\u003eInput Signal Level 20mV to 28V\u003c\/li\u003e\n\u003cli\u003ePCB dimensions: 31.12 x 12.86 mm\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eApplications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eVariable Reluctance Magnetic Pickup to Voltage Converter\u003c\/li\u003e\n\u003cli\u003eSound Signal to Voltage Converter\u003c\/li\u003e\n\u003cli\u003eSpeedo Meter\u003c\/li\u003e\n\u003cli\u003eUnder or Over Speed Sensing\u003c\/li\u003e\n\u003cli\u003eTouch Sensor\u003c\/li\u003e\n\u003cli\u003eFrequency to Voltage Converter\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"dotfry","offers":[{"title":"Default Title","offer_id":47222660300972,"sku":"B133","price":12.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0757\/6436\/7532\/files\/B133a.jpg?v=1789557233","url":"https:\/\/dotfry.com\/products\/frequency-to-voltage-converter-tachometer-variable-reluctance-magnetic-pickup-to-voltage-converter","provider":"dotfry","version":"1.0","type":"link"}