(2) RELAYS, Miniature HAMLIN Magnetic REED Relays (or *Proximity SWITCH*)

Description: (2 Miniature 12 Volt Hamlin Reed Relays 0806 Most purchases qualify for a ** Combined Shipping Discount ** Fast eMail Fast Shipping Guaranteed Good-on-Arrival (2) Magnetic Reed Relays SPST N.O. Contact, 12 VDC (1000 Ω) *DIY Experimenters: Can be rigged as sensitive N.O., or even N.C. proximity switches. Check out the *Alternative Applications* section below. Price is for (2) relays. SPST N.O. (Normally Open) Rugged: Encased in Plastic & Steel Magnetically Shielded* FAST 1.0 ms Response Time 0.5 Amp Switching, 1.2 Amp Load 200 Volt Switching, 250 V Breakdown Pin Spacing: 0.2" UL Rated Datasheet for Hamlin HE3621: https://linearparts.com/documents/HE3600.pdf ( Equivalent to HE3621A1200 ) *Alternative Applications* Transform Reed Relay into Super Sensitive Proximity Switch These relays have great potential as Super-Sensitive Magnetic Proximity Switches. Our lab tests revealed some interesting possibilities. These notes are only intended to share our limited test results with several samples. Important Note: Results varied from unit to unit. Since this is an undocumented alternative application and beyond the manufacturer's published specifications, your results will probably vary from ours. So experimentation is the keyword. First, we tested (12) relays to characterize the pull-in / drop-out voltages. All closed by 3.5 volts going up and opened by 2.8 volts going down. Based on the dozen samples, allowing for hysteresis, we believe most, if not all, will pull in by 4 volts and drop out below 2.5 volts. Enhanced Sensitivity Magnetic Proximity Switch Remove the magnetic shield to use it as a proximity switch. Use a thin screwdriver blade to pry off the metal shell. We used an ordinary refrigerator magnet (left) for testing. It closed our test switch at a distance of about ¾". That's about the same as a typical proximity switch. Orientation is important. The axis of the magnetic field and switch should be parallel. (Note: This listing is for the relays only. Refrigerator magnets and pennies are NOT included. But please read below as we do offer some freebies just for asking.) Now here's the neat stuff. With a variable power supply, we carefully biased the coil just below the drop-out point. Using the same magnet, the sensitivity increased to about a foot. The magnetic field has to be in phase with the coil's field. That's at least 10x the distance unbiased. But it gets better! Next we tried the reverse approach and increased the coil bias just until the switch closed (turned on). Then, after turning the refrigerator magnet around 180 degrees, to place it out of phase with the the electro-magnetic field, we could turn the switch off with the magnet at a distance of about a foot. This experiment illustrated how this N.O. relay can be used as a sensitive N.C. proximity switch too. Cool. Remember: Results may vary from relay to relay. Allow for hysteresis. Particularly, avoid setting the bias current too close to the thresholds for either the N.O. or N.C. states. A buffer zone may reduce the sensitivity, but reliability and repeatability will be improved. FREEBIES, but only if you ask when making payment. Our tiny micro-magnet (right) will switch at about ¼". Biasing the coil just barely on, or barely off and provided the magnet was properly oriented for the task, we could flip the switch from about an inch away. They are small enough to be easily hidden and virtually undetectable: under a watch band, in a ballpoint pen, sewn in a shirt sleeve, in a soda straw, a book binding - you get the idea. We'll give you (2), just for the asking, at no charge per lot of relays. Your payment does not include the magnets. Magnets are NOT part of the listing and will NOT be shipped with the relays unless you ask for them when making your payment. Just ask for the free Micro-Magnets. Now this is way out on the fringe but you may find it interesting. Miscellaneous findings (may or may not be reproducible): As the bias current is slowly adjusted, each relay performs differently at it's magnetic threshold. Some switch rather abruptly, while others go through a very brief transition where there is noticeable contact resistance. Our test circuit switched 5 volts through a 1K resistor to a LED. We found some relays have a critical bias setting where the LED glows dimly. We carefully adjusted one relay to the point where the LED was at about half intensity - the contact resistance appeared to act as a current control. Incredibly, with some relays, we could vary the intensity of the LED with the refrigerator magnet at a distance of 1 to 2 feet. (26 inches was the most sensitive.) At that great distance, the permanent magnet's strength wasn't strong enough to either fully actuate or deactuate the switch, but only vary the LED brightness. It wouldn't be fair to say it would "switch" with the magnet at 1 foot, but it is accurate to say it could sense the magnetic field at foot or more. That's amazing. But other samples worked much differently. With careful biasing of the coil current, most switches tripped solidly with the magnet at about 4 to 6 inches. Most relays will probably fall into the later category since there is a 'capture' effect with the reed contacts as they close. Their mutual attraction increases exponentially as the gap closes. Our theory is that a slight misalignment of the contacts causes them to close gradually with a slowly changing magnetic field. Without that sharp snap it transitions through a very brief actuation "gray zone". One more application thought. You can place a magnet just out of range of the switch and then bridge the gap with some ferrous material. For instance, you could count nails on a conveyor belt. The switch on one side would be unaffected by the magnet on opposite side until a nail passes in between to conduct the magnetic flux across the belt. Relay or Sensitive N.O. / N.C. Proximity Switch or Super Sensitive Magnetic Field Sensor? We'd like to hear what you think. SRH-2 ************************************* ham radio etronic e-tronic hamtronic qba BootsParts USA boots PAYMENT and SHIPPING ** We offer a Combined Shipping Discount for most purchases (excluding books) if paid with ONE SINGLE PAYMENT with eBay's SHOPPING CART ** Condition of Goods Unless otherwise noted above: NOS (New Old Stock) or better, clean, unused 30 day Non-DOA, Good-on-Arrival Guarantee Untested, but NO JUNK or suspect parts PCB parts are thru-hole, NO SMD/SMT Small parts may be bulk packed Manufacturers and Date Codes may vary Attention International bidders only: Sorry, we ship to US ZIP Codes ONLY. We DO NOT ship Internationally. We ONLY ship to Registered US PayPal addresses. We DO NOT accept INTERNATIONAL PayPal payments. IMPORTANT: The parts we sell are categorized as new because they are unused, but many of our parts are those rare, hard-to-find, discontinued, manufacturing surplus and / or old stock commonly known in the parts business as 'NOS' (New Old Stock). Some of our stock pictures show date codes which may vary from the actual product shipped. Parts from a larger OEM package may be repacked for smaller lot size orders or for more practical handling and shipping. We strive to give full and accurate descriptions to earn your 5-Star Feedback. Any known deficiencies are listed in the detailed description. Datasheets are provided when available. Some datasheets may be close but not a perfect match because of part revisions or because they may be from a different manufacturer. If you have any questions concerning our products please email us before purchasing. Your complete satisfaction is important to us before and after the sale. Thank you.

Price: 8.95 USD

Location: Garland, Texas

End Time: 2024-09-01T05:35:04.000Z

Shipping Cost: 3.5 USD