File:Relay Driver Circuit using PNP Transistor.jpg
Relay_Driver_Circuit_using_PNP_Transistor.jpg (348 × 357 pixels, file size: 9 KB, MIME type: image/jpeg)
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Summary[edit]
| Description |
English: Referring the figure, any small signal PNP BJT such as BC557 can be used to create a simple relay driver circuit for operating a relay ON/OFF through an external trigger.
Here the relay switches ON as soon as power is switched ON. The relay can be switched OFF by connecting the transistor base with the positive line. The freewheeling diode across the relay coil is important as it ensures safety to the transistor from the reverse EMF of the relay coil whenever the relay is switched OFF. This diode can be a 1N4148 diode. The base resistor can be calculated using the following formula: R = (Supply Voltage - Base Forward Voltage) x hFE / Load Current The load current here is the relay coil current. This can be found using ohms law if the relay coil resistance is known. For any assistance regarding electronic circuits you can reach out to me though my website homemade-circuits |
| Date | |
| Source | Own work |
| Author | Swagatam Majumdar |
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 04:04, 21 September 2023 | | 348 × 357 (9 KB) | Swagatam Majumdar (talk | contribs) | Uploaded own work with UploadWizard |
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