Typowy układ z diodą Zenera.

https://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWcAmWDLMgZgBxmcgCxg4CcSWkIShW1ApgLRhgBQAXiAGyHinLdeYQrwEATegDMAhgFcANgBdG7egDt6AJ1YBzQXwE8QBXlUi6UOA5eNEoUC4xxUw-EE6on75gG7vn1h7gIvYQYHAglBGYZlDQCKyaNq4C+FbCpuDwie6E6fiRqQUu2QDu-i4hQSwC5uXVBYx54MWs5VhFhkKt5UY1+hkOvd2pyPm1bckFacGmrITY1qRcIMQrmFZmAPo8W5BbeVwA7FvhW1jQyFvMW1f7WPOLKba8a5FYK9u7+2tYp7DwQFAuBgJhYUjnS7A6GQQhMBbXMC3PbnVi4VYgABiECojEwxlxEAAagB7JTSHT0VhAA

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