{"product_id":"oh137-unipolar-hall-effect-switch","title":"OH137 Unipolar Hall Effect Switch Sensor – TO-92S, 4V–24V","description":"\u003cstyle\u003e\n.nznpd{--o:#F57C00;--od:#E65100;--ink:#0F172A;--mut:#5b6573;--line:#E8ECF0;--soft:#F7F8FA;max-width:1120px;margin:0 auto;color:var(--ink);font-family:inherit;line-height:1.6}\n.nznpd,.nznpd *{box-sizing:border-box}\n.nznpd p{margin:0;color:var(--mut);font-size:15px;line-height:1.65}\n.nznpd strong{color:var(--ink)}\n.nznpd__intro{font-size:16px;color:var(--ink);font-weight:500;line-height:1.6;max-width:72ch}\n.nznpd__checks{list-style:none;padding:0;margin:22px 0 0;display:grid;grid-template-columns:repeat(2,1fr);column-gap:26px;row-gap:13px}\n.nznpd__checks li{display:flex;gap:11px;align-items:flex-start;font-size:15px;color:var(--ink);line-height:1.45}\n.nznpd__checks li::before{content:\"\\2713\";flex:0 0 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class=\"nznpd__lead\"\u003e\n\u003cp class=\"nznpd__intro\"\u003eThe OH137 is a unipolar Hall effect switch IC fabricated with reverse voltage protection, a Schmitt trigger, and an open-collector output stage — converting a south-pole magnetic field into a clean digital LOW signal. Unlike a bipolar latch, it resets automatically when the magnet is removed, making it ideal for speed sensing, position detection, and contactless switching across a wide 4V–24V supply range.\u003c\/p\u003e\n\u003cbr\u003e\n\u003cul class=\"nznpd__checks\"\u003e\n\u003cli\u003eUnipolar switch — south pole activates, output pulls LOW; no magnet = HIGH\u003c\/li\u003e\n\u003cli\u003e4V–24V supply range, 25 mA open-collector output\u003c\/li\u003e\n\u003cli\u003eFast switching — 0.13 µs rise, 0.10 µs fall time\u003c\/li\u003e\n\u003cli\u003eSchmitt trigger hysteresis — clean switching, no chatter\u003c\/li\u003e\n\u003cli\u003eReverse polarity protection built in\u003c\/li\u003e\n\u003cli\u003e−40°C to +85°C operating temperature range\u003c\/li\u003e\n\u003cli\u003eTO-92S through-hole package, direct logic interface\u003c\/li\u003e\n\u003cli\u003eCompatible with Arduino, ESP32, Raspberry Pi and more\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\n\u003csection class=\"nznpd__block\"\u003e\n\u003ch3 class=\"nznpd__h\"\u003eSpecifications\u003c\/h3\u003e\n\u003cbr\u003e\n\u003cdiv class=\"nznpd__specs\"\u003e\n\u003cdiv class=\"nznpd__spec\"\u003e\n\u003cspan\u003eModel\u003c\/span\u003e\u003cstrong\u003eOH137 (OH137A0)\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"nznpd__spec\"\u003e\n\u003cspan\u003eSwitch Type\u003c\/span\u003e\u003cstrong\u003eUnipolar — south pole only, non-latching\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"nznpd__spec\"\u003e\n\u003cspan\u003eSupply Voltage (VCC)\u003c\/span\u003e\u003cstrong\u003e4.5V – 24V DC\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"nznpd__spec\"\u003e\n\u003cspan\u003eOutput Current (IO)\u003c\/span\u003e\u003cstrong\u003e25 mA max\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"nznpd__spec\"\u003e\n\u003cspan\u003eOutput Type\u003c\/span\u003e\u003cstrong\u003eOpen-collector, active LOW\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"nznpd__spec\"\u003e\n\u003cspan\u003eOperating Temperature (TA)\u003c\/span\u003e\u003cstrong\u003e−40°C to +85°C\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"nznpd__spec\"\u003e\n\u003cspan\u003eStorage Temperature (TS)\u003c\/span\u003e\u003cstrong\u003e−55°C to +150°C\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"nznpd__spec\"\u003e\n\u003cspan\u003eOutput Rise Time\u003c\/span\u003e\u003cstrong\u003e0.13 µs typical\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"nznpd__spec\"\u003e\n\u003cspan\u003eOutput Fall Time\u003c\/span\u003e\u003cstrong\u003e0.10 µs typical\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"nznpd__spec\"\u003e\n\u003cspan\u003eHysteresis\u003c\/span\u003e\u003cstrong\u003e6–8 mT Schmitt trigger\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"nznpd__spec\"\u003e\n\u003cspan\u003ePackage\u003c\/span\u003e\u003cstrong\u003eTO-92S, 3-pin through-hole\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"nznpd__spec\"\u003e\n\u003cspan\u003eMCU Compatibility\u003c\/span\u003e\u003cstrong\u003eArduino, ESP32, Raspberry Pi, STM32, PIC\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\n\u003csection class=\"nznpd__block\"\u003e\n\u003ch3 class=\"nznpd__h\"\u003eWhat's in the pack\u003c\/h3\u003e\n\u003cbr\u003e\n\u003cdiv class=\"nznpd__included\"\u003e\n\u003cdiv class=\"nznpd__qty\"\u003e×\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eOH137 Unipolar Hall Effect Switch ICs\u003c\/strong\u003e\n\u003cp\u003eQuantity as selected. TO-92S through-hole package, ready to use.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\n\u003csection class=\"nznpd__block\"\u003e\n\u003ch3 class=\"nznpd__h\"\u003eGreat for\u003c\/h3\u003e\n\u003cbr\u003e\n\u003cdiv class=\"nznpd__uses\"\u003e\n\u003cdiv class=\"nznpd__use\"\u003eSpeed and RPM sensing on motors, wheels and shafts\u003c\/div\u003e\n\u003cdiv class=\"nznpd__use\"\u003ePosition and end-stop detection in CNC and robotics\u003c\/div\u003e\n\u003cdiv class=\"nznpd__use\"\u003eDoor, lid and panel open\/close sensing\u003c\/div\u003e\n\u003cdiv class=\"nznpd__use\"\u003eFlow measurement with impeller-based sensors\u003c\/div\u003e\n\u003cdiv class=\"nznpd__use\"\u003eTraffic and gear tooth detection\u003c\/div\u003e\n\u003cdiv class=\"nznpd__use\"\u003eNon-contact switching in home appliances and power tools\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\n\u003csection class=\"nznpd__block\"\u003e\n\u003cdiv class=\"nznpd__qs\"\u003e\n\u003ch3\u003eGetting started\u003c\/h3\u003e\n\u003col class=\"nznpd__steps\"\u003e\n\u003cli\u003e\u003cdiv\u003e\n\u003cstrong\u003eOrient the sensor\u003c\/strong\u003e\u003cp\u003eHold the TO-92S package with the flat printed face toward you, legs pointing down. Pins 1, 2, 3 run left to right. The flat face is the active sensing surface.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cdiv\u003e\n\u003cstrong\u003eWire power and ground\u003c\/strong\u003e\u003cp\u003eConnect Pin 1 (VCC) to your supply — 5V for Arduino, or 5V Vin on ESP32 (minimum 4.5V required). Connect Pin 2 to GND.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cdiv\u003e\n\u003cstrong\u003eConnect the output with a pull-up\u003c\/strong\u003e\u003cp\u003eConnect Pin 3 (OUT) to a digital GPIO. Use \u003ccode\u003epinMode(pin, INPUT_PULLUP)\u003c\/code\u003e in Arduino, or add a 10 kΩ resistor from Pin 3 to VCC.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003cli\u003e\u003cdiv\u003e\n\u003cstrong\u003eRead the output\u003c\/strong\u003e\u003cp\u003e\u003ccode\u003edigitalRead()\u003c\/code\u003e returns LOW when a south-pole magnet faces the flat surface, HIGH otherwise. Use \u003ccode\u003eattachInterrupt()\u003c\/code\u003e for RPM counting without polling.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\n\u003csection class=\"nznpd__block\"\u003e\n\u003ch3 class=\"nznpd__h\"\u003eHow it works\u003c\/h3\u003e\n\u003cdiv class=\"nzndemo\"\u003e\n  \u003cdiv class=\"nzndemo__layout\"\u003e\n    \u003cdiv\u003e\n      \u003cdiv class=\"nzndemo__canvas\"\u003e\n        \u003csvg id=\"oh137-svg\" viewbox=\"0 0 400 210\" width=\"100%\" style=\"max-width:420px;overflow:visible\"\u003e\n          \u003cg id=\"oh137-mag\" transform=\"translate(8,62)\"\u003e\n            \u003crect id=\"oh137-left-rect\" x=\"0\" y=\"0\" width=\"56\" height=\"72\" rx=\"5\" fill=\"#DDEEFF\" stroke=\"#5B9BD5\" stroke-width=\"1.5\"\u003e\u003c\/rect\u003e\n            \u003ctext id=\"oh137-left-lbl\" x=\"28\" y=\"43\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#1a4a7a\"\u003eS\u003c\/text\u003e\n            \u003crect id=\"oh137-right-rect\" x=\"56\" y=\"0\" width=\"56\" height=\"72\" rx=\"5\" fill=\"#FDDDD9\" stroke=\"#E05C45\" stroke-width=\"1.5\"\u003e\u003c\/rect\u003e\n            \u003ctext id=\"oh137-right-lbl\" x=\"84\" y=\"43\" text-anchor=\"middle\" font-size=\"20\" font-weight=\"700\" fill=\"#7a1a0a\"\u003eN\u003c\/text\u003e\n            \u003ctext x=\"56\" y=\"90\" text-anchor=\"middle\" font-size=\"11\" fill=\"#5b6573\"\u003emagnet\u003c\/text\u003e\n          \u003c\/g\u003e\n          \u003cg id=\"oh137-lines\" opacity=\"0\"\u003e\n            \u003cline x1=\"130\" y1=\"84\" x2=\"182\" y2=\"98\" stroke=\"#5B9BD5\" stroke-width=\"1\" stroke-dasharray=\"4,3\"\u003e\u003c\/line\u003e\n            \u003cline x1=\"130\" y1=\"98\" x2=\"182\" y2=\"98\" stroke=\"#5B9BD5\" stroke-width=\"1\" stroke-dasharray=\"4,3\"\u003e\u003c\/line\u003e\n            \u003cline x1=\"130\" y1=\"112\" x2=\"182\" y2=\"98\" stroke=\"#5B9BD5\" stroke-width=\"1\" stroke-dasharray=\"4,3\"\u003e\u003c\/line\u003e\n            \u003cpolygon id=\"oh137-arr1\" points=\"182,93 192,98 182,103\" fill=\"#5B9BD5\"\u003e\u003c\/polygon\u003e\n          \u003c\/g\u003e\n          \u003cg transform=\"translate(192,46)\"\u003e\n            \u003crect x=\"0\" y=\"0\" width=\"96\" height=\"90\" rx=\"5\" fill=\"#fff\" stroke=\"#CBD5E0\" stroke-width=\"1.5\"\u003e\u003c\/rect\u003e\n            \u003crect x=\"0\" y=\"0\" width=\"6\" height=\"90\" rx=\"2\" fill=\"#F0F4F8\"\u003e\u003c\/rect\u003e\n            \u003ctext x=\"51\" y=\"30\" text-anchor=\"middle\" font-size=\"11\" font-weight=\"700\" fill=\"#0F172A\"\u003eOH137\u003c\/text\u003e\n            \u003ctext x=\"51\" y=\"50\" text-anchor=\"middle\" font-size=\"10\" fill=\"#5b6573\"\u003eflat face\u003c\/text\u003e\n            \u003cline x1=\"20\" y1=\"90\" x2=\"20\" y2=\"118\" stroke=\"#0F172A\" stroke-width=\"2\"\u003e\u003c\/line\u003e\n            \u003cline x1=\"48\" y1=\"90\" x2=\"48\" y2=\"118\" stroke=\"#0F172A\" stroke-width=\"2\"\u003e\u003c\/line\u003e\n            \u003cline x1=\"76\" y1=\"90\" x2=\"76\" y2=\"118\" stroke=\"#0F172A\" stroke-width=\"2\"\u003e\u003c\/line\u003e\n            \u003ctext x=\"20\" y=\"134\" text-anchor=\"middle\" font-size=\"10\" fill=\"#5b6573\"\u003eVCC\u003c\/text\u003e\n            \u003ctext x=\"48\" y=\"134\" text-anchor=\"middle\" font-size=\"10\" fill=\"#5b6573\"\u003eGND\u003c\/text\u003e\n            \u003ctext x=\"76\" y=\"134\" text-anchor=\"middle\" font-size=\"10\" fill=\"#5b6573\"\u003eOUT\u003c\/text\u003e\n          \u003c\/g\u003e\n          \u003cline x1=\"288\" y1=\"98\" x2=\"322\" y2=\"98\" stroke=\"#CBD5E0\" stroke-width=\"1.5\"\u003e\u003c\/line\u003e\n          \u003ccircle id=\"oh137-led\" cx=\"338\" cy=\"98\" r=\"14\" fill=\"#F7F8FA\" stroke=\"#CBD5E0\" stroke-width=\"1.5\"\u003e\u003c\/circle\u003e\n          \u003ctext id=\"oh137-ledlbl\" x=\"338\" y=\"79\" text-anchor=\"middle\" font-size=\"11\" font-weight=\"700\" fill=\"#5b6573\"\u003eHIGH\u003c\/text\u003e\n          \u003ctext x=\"338\" y=\"122\" text-anchor=\"middle\" font-size=\"10\" fill=\"#5b6573\"\u003eLED\u003c\/text\u003e\n        \u003c\/svg\u003e\n      \u003c\/div\u003e\n    \u003c\/div\u003e\n    \u003cdiv class=\"nzndemo__controls\"\u003e\n      \u003cdiv\u003e\n        \u003cdiv class=\"nzndemo__label\"\u003eApply magnetic field\u003c\/div\u003e\n        \u003cdiv class=\"nzndemo__btns\"\u003e\n          \u003cbutton class=\"nzndemo__btn\" id=\"oh137-bs\" onclick=\"oh137Apply('south')\"\u003eSouth pole\u003cbr\u003efacing sensor\u003c\/button\u003e\n          \u003cbutton class=\"nzndemo__btn\" id=\"oh137-bn\" onclick=\"oh137Apply('north')\"\u003eNorth pole\u003cbr\u003efacing sensor\u003c\/button\u003e\n          \u003cbutton class=\"nzndemo__btn nzndemo__btn-full\" id=\"oh137-br\" onclick=\"oh137Apply('none')\"\u003eRemove magnet\u003c\/button\u003e\n        \u003c\/div\u003e\n      \u003c\/div\u003e\n      \u003cdiv class=\"nzndemo__status\"\u003e\n        \u003cdiv class=\"nzndemo__label\" style=\"margin-bottom:2px\"\u003eOutput state\u003c\/div\u003e\n        \u003cdiv class=\"nzndemo__row\"\u003e\n\u003cspan class=\"nzndemo__rowkey\"\u003ePin 3 (OUT)\u003c\/span\u003e\u003cspan class=\"nzndemo__rowval\" id=\"oh137-pin\"\u003eHIGH\u003c\/span\u003e\n\u003c\/div\u003e\n        \u003cdiv class=\"nzndemo__row\"\u003e\n\u003cspan class=\"nzndemo__rowkey\"\u003eState\u003c\/span\u003e\u003cspan class=\"nzndemo__badge\" id=\"oh137-badge\"\u003eoff\u003c\/span\u003e\n\u003c\/div\u003e\n        \u003cdiv class=\"nzndemo__row\"\u003e\n\u003cspan class=\"nzndemo__rowkey\"\u003eMagnet\u003c\/span\u003e\u003cspan class=\"nzndemo__rowval\" id=\"oh137-mag-lbl\"\u003enone\u003c\/span\u003e\n\u003c\/div\u003e\n      \u003c\/div\u003e\n      \u003cdiv class=\"nzndemo__info\"\u003e\n        \u003cdiv class=\"nzndemo__info-title\" id=\"oh137-ititle\"\u003eNo magnet present\u003c\/div\u003e\n        \u003cdiv class=\"nzndemo__info-body\" id=\"oh137-ibody\"\u003eOutput is HIGH via pull-up. The OH137 resets automatically — no magnet means no activation.\u003c\/div\u003e\n      \u003c\/div\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"nzndemo__concepts\"\u003e\n    \u003cdiv class=\"nzndemo__concept\"\u003e\n      \u003cdiv class=\"nzndemo__concept-title\"\u003eSouth pole only\u003c\/div\u003e\n      \u003cdiv class=\"nzndemo__concept-body\"\u003eOnly a south-facing pole activates the sensor. North pole has zero effect on the output.\u003c\/div\u003e\n    \u003c\/div\u003e\n    \u003cdiv class=\"nzndemo__concept\"\u003e\n      \u003cdiv class=\"nzndemo__concept-title\"\u003eNon-latching\u003c\/div\u003e\n      \u003cdiv class=\"nzndemo__concept-body\"\u003eOutput goes LOW while the magnet is present and returns HIGH immediately when removed. No memory.\u003c\/div\u003e\n    \u003c\/div\u003e\n    \u003cdiv class=\"nzndemo__concept\"\u003e\n      \u003cdiv class=\"nzndemo__concept-title\"\u003eSchmitt trigger\u003c\/div\u003e\n      \u003cdiv class=\"nzndemo__concept-body\"\u003e6–8 mT hysteresis prevents chatter at the switching threshold for clean, bounce-free transitions.\u003c\/div\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"nzndemo__vs\"\u003e\n\u003cstrong\u003eUnipolar switch vs bipolar latch:\u003c\/strong\u003e The OH137 only responds to the south pole and resets when the magnet is removed — simple and predictable. The US1881 bipolar latch responds to both poles and holds state after removal. Use the OH137 for RPM counting and proximity sensing; use the US1881 for BLDC commutation and toggle switching.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\n\u003csection class=\"nznpd__block\"\u003e\n\u003ch3 class=\"nznpd__h\"\u003eCommon questions\u003c\/h3\u003e\n\u003cbr\u003e\n\u003cdiv class=\"nznpd__faqs\"\u003e\n\u003cdetails class=\"nznpd__faq\" open\u003e\n\u003csummary\u003eDoes the north pole trigger the OH137?\u003c\/summary\u003e\n\u003cp\u003eNo — the OH137 is unipolar and only responds to a south magnetic pole facing the flat face. The north pole has no effect on the output. If you need both poles to trigger switching, see the US1881 bipolar Hall latch.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"nznpd__faq\"\u003e\n\u003csummary\u003eDoes the output hold state when the magnet is removed?\u003c\/summary\u003e\n\u003cp\u003eNo. The OH137 is non-latching — the output goes LOW while the south pole is present and returns HIGH as soon as the magnet is removed. There is no memory. For latching behaviour, use the US1881.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"nznpd__faq\"\u003e\n\u003csummary\u003eDo I need a pull-up resistor?\u003c\/summary\u003e\n\u003cp\u003eYes. The output is open-collector, so it needs a pull-up to read HIGH. Use \u003ccode\u003eINPUT_PULLUP\u003c\/code\u003e in Arduino to enable the internal pull-up, or wire a 10 kΩ resistor from Pin 3 to VCC.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"nznpd__faq\"\u003e\n\u003csummary\u003eCan I use it with a 3.3V ESP32?\u003c\/summary\u003e\n\u003cp\u003eYes, with care. Power Pin 1 (VCC) from the ESP32's 5V Vin rail — the sensor needs a minimum of 4.5V on VCC. The open-collector output on Pin 3 is safe for a 3.3V GPIO input provided the pull-up resistor goes to 3.3V, not 5V.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails class=\"nznpd__faq\"\u003e\n\u003csummary\u003eWhat's the maximum switching speed?\u003c\/summary\u003e\n\u003cp\u003eThe OH137 has a 0.13 µs rise time and 0.10 µs fall time, giving it a wide operating frequency suitable for high-speed RPM counting and gear tooth detection. Use \u003ccode\u003eattachInterrupt()\u003c\/code\u003e rather than polling for best accuracy at high speeds.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e\n\u003c\/section\u003e\n\n\u003cp class=\"nznpd__note\"\u003e\u003cstrong\u003eSouth pole only:\u003c\/strong\u003e The OH137 is unipolar — the north pole has no effect on the output. A pull-up resistor is always required; the open-collector output will float without one. For switching with both poles, see the US1881 bipolar Hall latch.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cscript\u003e\n(function(){\nvar state={pole:'none'};\nvar msgs={\n  south:{t:'South pole applied — output LOW',b:'The south pole exceeds the \u003cstrong\u003eoperate point\u003c\/strong\u003e. Output pulls LOW via the open-collector transistor — the LED turns on. Remove the magnet and it immediately resets HIGH.'},\n  north:{t:'North pole — no effect',b:'The OH137 is \u003cstrong\u003eunipolar\u003c\/strong\u003e — the north pole has no effect on the output. Pin 3 remains HIGH. Only the south pole can activate this sensor.'},\n  none:{t:'No magnet present',b:'Output is \u003cstrong\u003eHIGH via pull-up\u003c\/strong\u003e. The OH137 resets automatically — no magnet means no activation. This is the default idle state.'}\n};\nfunction oh137Apply(pole){state.pole=pole;render();}\nwindow.oh137Apply=oh137Apply;\nfunction setMagnetPoles(pole){\n  var lr=document.getElementById('oh137-left-rect');\n  var ll=document.getElementById('oh137-left-lbl');\n  var rr=document.getElementById('oh137-right-rect');\n  var rl=document.getElementById('oh137-right-lbl');\n  if(!lr) return;\n  if(pole==='south'){\n    lr.setAttribute('fill','#FDDDD9');lr.setAttribute('stroke','#E05C45');\n    ll.textContent='N';ll.setAttribute('fill','#7a1a0a');\n    rr.setAttribute('fill','#DDEEFF');rr.setAttribute('stroke','#5B9BD5');\n    rl.textContent='S';rl.setAttribute('fill','#1a4a7a');\n  } else if(pole==='north'){\n    lr.setAttribute('fill','#DDEEFF');lr.setAttribute('stroke','#5B9BD5');\n    ll.textContent='S';ll.setAttribute('fill','#1a4a7a');\n    rr.setAttribute('fill','#FDDDD9');rr.setAttribute('stroke','#E05C45');\n    rl.textContent='N';rl.setAttribute('fill','#7a1a0a');\n  } else {\n    lr.setAttribute('fill','#DDEEFF');lr.setAttribute('stroke','#5B9BD5');\n    ll.textContent='S';ll.setAttribute('fill','#1a4a7a');\n    rr.setAttribute('fill','#FDDDD9');rr.setAttribute('stroke','#E05C45');\n    rl.textContent='N';rl.setAttribute('fill','#7a1a0a');\n  }\n}\nfunction render(){\n  var p=state.pole;\n  var isOn=p==='south';\n  var bs=document.getElementById('oh137-bs');\n  var bn=document.getElementById('oh137-bn');\n  var br=document.getElementById('oh137-br');\n  if(bs) bs.className='nzndemo__btn'+(p==='south'?' s-active':'');\n  if(bn) bn.className='nzndemo__btn'+(p==='north'?' n-active':'');\n  if(br) br.className='nzndemo__btn nzndemo__btn-full'+(p==='none'?' r-active':'');\n  var led=document.getElementById('oh137-led');\n  var ledlbl=document.getElementById('oh137-ledlbl');\n  var pin=document.getElementById('oh137-pin');\n  var badge=document.getElementById('oh137-badge');\n  var maglbl=document.getElementById('oh137-mag-lbl');\n  var ititle=document.getElementById('oh137-ititle');\n  var ibody=document.getElementById('oh137-ibody');\n  var lines=document.getElementById('oh137-lines');\n  var magG=document.getElementById('oh137-mag');\n  if(led){led.setAttribute('fill',isOn?'#22C55E':'#F7F8FA');led.setAttribute('stroke',isOn?'#16A34A':'#CBD5E0');}\n  if(ledlbl){ledlbl.textContent=isOn?'LOW':'HIGH';ledlbl.setAttribute('fill',isOn?'#15803D':'#5b6573');}\n  if(pin) pin.textContent=isOn?'LOW (0V)':'HIGH';\n  if(badge){badge.className='nzndemo__badge'+(isOn?' bon':' boff');badge.textContent=isOn?'on':'off';}\n  if(maglbl) maglbl.textContent=p==='south'?'south pole':p==='north'?'north pole':'removed';\n  if(magG) magG.setAttribute('transform',(p==='south'||p==='north')?'translate(52,62)':'translate(8,62)');\n  setMagnetPoles(p);\n  if(lines){\n    if(p==='south'||p==='north'){\n      lines.style.opacity='1';\n      var lns=lines.querySelectorAll('line');\n      var arr=document.getElementById('oh137-arr1');\n      var col=p==='south'?'#5B9BD5':'#CBD5E0';\n      lns.forEach(function(ln){ln.setAttribute('stroke',col);});\n      if(arr) arr.setAttribute('fill',col);\n      if(p==='north'){\n        lns[0].setAttribute('x1','182');lns[0].setAttribute('x2','130');\n        lns[1].setAttribute('x1','182');lns[1].setAttribute('x2','130');\n        lns[2].setAttribute('x1','182');lns[2].setAttribute('x2','130');\n        if(arr) arr.setAttribute('points','130,93 120,98 130,103');\n      } else {\n        lns[0].setAttribute('x1','130');lns[0].setAttribute('x2','182');\n        lns[1].setAttribute('x1','130');lns[1].setAttribute('x2','182');\n        lns[2].setAttribute('x1','130');lns[2].setAttribute('x2','182');\n        if(arr) arr.setAttribute('points','182,93 192,98 182,103');\n      }\n    } else {\n      lines.style.opacity='0';\n    }\n  }\n  if(ititle) ititle.textContent=msgs[p].t;\n  if(ibody) ibody.innerHTML=msgs[p].b;\n}\nrender();\n})();\n\u003c\/script\u003e","brand":"NZN Electronics","offers":[{"title":"Default Title","offer_id":42868142211168,"sku":"OH137-HALL-10PK","price":1.09,"currency_code":"NZD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0664\/6127\/0112\/files\/OH137ProductHero.png?v=1781519909","url":"https:\/\/www.nznelectronics.co.nz\/products\/oh137-unipolar-hall-effect-switch","provider":"NZN Electronics","version":"1.0","type":"link"}