Check the listing for details. (6 pc set) = (4) LM317 Positive + (2) LM337 Negative ---- VARIABLE Regulators. Condition: New. Listed at 8.85 USD. LM317 and LM337 Variable Voltage Regulators 0211 Most purchases qualify for a ** Combined Shipping Discount ** Fast eMail Fast Shipping Guaranteed Good-on-Arrival (4) LM317 POSITIVE and (2) LM337 NEGATIVE Variable Voltage Regulators Adjustable from 1.2 to 37 Volts @ 1.5 Amp Price is for a mixed set of (6) pieces total. FEATURES: Positive LM317 & Negative LM337 Types Wide 1.2 to 37 Volt Variable Range 1.5+ Amp Output Few External Parts Required Internal Short and Thermal Protection Eliminates Stocking Many Fixed Values Simple Experimenter's Power Supply Brands On-Semi, STM, etc. TO-220 Datasheets: LM317 - https://linearparts.com/documents/LM317-on.pdf LM337 - https://linearparts.com/documents/LM337-on.pdf Notes: Refer to the left schematic above, R2 = 96 [ VOUT - 1.33 ] Simple formula works for both the LM317 and LM337 and can be used to calculate R2 for your choice of output voltage. R1 must be 120 Ω. It will get you within a few percent or better. Use a trimmer if you need better precision or a panel pot if you want it to be externally adjustable. Caution: The 'Input' and 'Output' pin order is different between the '317 and '337. See drawing above. Verify your wiring with the datasheet before applying power. The current limiter circuit (left) will work equally well with either the '317 or '337. You can use either part in the same circuit simply by observing polarity. Replace the fixed resistor with a variable resistor and you can make a variable current source. A voltage regulator and current limiter will make a handy bench supply. 3X7-6 800 pixels REVISED Rev11/05/20 added sentence to check our store for other listed quantities --> ************************************* 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 addresses. We DO NOT accept INTERNATIONAL 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. See our store for other listed quantities. 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. 111521