how do I use resistors of certain values to get 19vDC down to 18vDC?
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

 Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
 17th February 2013, 11:49 PM #1 realflow100   diyAudio Member   Join Date: Sep 2012 how do I use resistors of certain values to get 19vDC down to 18vDC? What kind of resistors would I need? And what would their values be?
 17th February 2013, 11:51 PM #2 john65b   diyAudio Member     Join Date: Jan 2005 Location: Chicago You need to know the current for the required 1 volt voltage drop. V=I*R. So your Resistor = 1 volt/your current... Why are you dropping one volt? __________________ I Speak Spanish to God, Italian to Women, French to Men, and German to My Horse. Charles V
 17th February 2013, 11:58 PM #3 realflow100   diyAudio Member   Join Date: Sep 2012 the device can put out around 2 amps exactly on the mark and no higher. I need to drop it one volt to run my laptop because the original laptop is gone and I don't want to buy a new charger for it. the charger I have runs fine and I wish to use it to run my newer laptop. but the laptop requires 18 volts DC and 1.5 amps and since I don't have a charger for it I wish to use the one I already have. if I can use some simple resistors to drop it by one volt that would be great.
 18th February 2013, 12:01 AM #4 DigitalJunkie   diyAudio Member   Join Date: Apr 2003 Location: Portland,Oregon Find a large 3A diode,and wire in in series with the positive lead. It will drop ~0.7V. That should be close enough. (~18.3V) My last laptop was rated for 16V,but it would run on anything in the 14-18V range. Edit:typo Last edited by DigitalJunkie; 18th February 2013 at 12:31 AM.
 18th February 2013, 12:03 AM #5 john65b   diyAudio Member     Join Date: Jan 2005 Location: Chicago I actually would not bother for 1 volt. the laptop should be able it take it with no issues...it will only take the amps it needs... __________________ I Speak Spanish to God, Italian to Women, French to Men, and German to My Horse. Charles V
 18th February 2013, 12:05 AM #6 realflow100   diyAudio Member   Join Date: Sep 2012 I tried it before but the laptop doesn't turn on. I see the lights flicker madly when its plugged in. not a good thing. it scares me. so I want to try dropping the voltage by one volt to see if it makes a difference.
 18th February 2013, 04:30 AM #7 gmphadte   diyAudio Member   Join Date: Jul 2003 Location: Dona paula, Goa Use two doides in series. The theoretical forward drop of a diode is 0.6 volts but it can be anywhere from 0.4 to 0.7 volts. Gajanan Phadte
 18th February 2013, 05:31 AM #8 sofaspud   diyAudio Member     Join Date: Nov 2005 Location: San Antonio Are you sure the laptop and supply are compatible? I never really looked into it much, but I assumed the supplies were 3-conductor, with the 3rd being part of the charge management. __________________ It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
 18th February 2013, 07:15 AM #9 madtecchy   diyAudio Member   Join Date: Dec 2010 Location: wigan What happened to the original charger for your newer laptop??????
 18th February 2013, 07:06 PM #10 Spiny   diyAudio Member     Join Date: Feb 2008 sofaspud is right, many have 3 conductors so they will not work without the correct brands powersupply. The plug has a central spike and the plus and minus are the inner and outer of the barrel. Dell are infamous for this - the actual charger could be standard but for the lockout from the data line. dell-laptops-reject-third-party-batteries-and-ac-adapterschargers-hardware-vendor-lock-in/ If this is not one of the trapped brands then a couple of 5Amp diodes in line will drop 1-1.2 v or so.

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Holton Precision Audio         CSS         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post dublin78 Power Supplies 6 14th March 2008 06:40 PM bowdown Solid State 15 28th March 2007 03:21 PM elviukai Pass Labs 15 29th May 2006 06:56 PM jaudio Chip Amps 0 19th March 2005 03:50 AM

 New To Site? Need Help?

All times are GMT. The time now is 09:19 AM.

 Home - Contact Us - Advertise - Rules - diyAudio Store - Sponsors - Privacy Statement - Terms of Service - Top - Opt-out policy

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.