tag:blogger.com,1999:blog-2554001380039969960.post6595472650930635524..comments2024-03-26T01:18:16.882+01:00Comments on LA3ZA Radio & Electronics: New gadget measures negative resistanceSverre Holmhttp://www.blogger.com/profile/08306221557326542499noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-2554001380039969960.post-39059611075018915412014-08-16T20:12:35.127+02:002014-08-16T20:12:35.127+02:00Well this theory can easily be tested by replacing...Well this theory can easily be tested by replacing the Samsung Galaxy with a resistive load that draws 980 mA and see what happens then when there are no extra filtering by the batteries. Another test would be to test the voltmeter and ampere meter in the USB Detector with a good and stable multimeter and see what differences there are if any. LA2RLhttps://www.blogger.com/profile/05546821474232313712noreply@blogger.comtag:blogger.com,1999:blog-2554001380039969960.post-29362477491343191902014-08-16T16:00:09.611+02:002014-08-16T16:00:09.611+02:00I found them cheaper here:
http://www.ebay.co.uk/...I found them cheaper here:<br /><br />http://www.ebay.co.uk/itm/Red-and-Blue-LED-USB-Charger-Doctor-Voltage-Current-Meter-Tester-Power-Detector-/281353987047?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item41820123e7<br /><br />73 Steve<br /><br />G1KQHG1KQHhttps://www.blogger.com/profile/04158573334769780015noreply@blogger.comtag:blogger.com,1999:blog-2554001380039969960.post-14728781780854716982014-08-16T10:49:58.109+02:002014-08-16T10:49:58.109+02:00There a good comment on Amateurradio.com by WA8WHP...There a good comment on <a href="http://www.amateurradio.com/new-gadget-measures-negative-resistance/" rel="nofollow">Amateurradio.com</a> by WA8WHP: <br /><br /><i>"The difference may be there is some ripple on the output which is filtered more by the batteries and not showing up on the DC voltmeter without the filtering."</i>Sverre Holmhttps://www.blogger.com/profile/08306221557326542499noreply@blogger.comtag:blogger.com,1999:blog-2554001380039969960.post-208791353417466562014-08-15T22:25:07.627+02:002014-08-15T22:25:07.627+02:00I guess this is due to the no load situation. The ...I guess this is due to the no load situation. The charger is surely using a switch-mode supply and many of these designs have problems under no load conditions. Many of them loose control and can even output much higher voltages than the design voltage. It is possible that the Samsung Galaxy charger guards against this situation by forcing the output to a fixed lower value when the feedback loop is open.<br />73 Frode, LA2RLLA2RLhttps://www.blogger.com/profile/05546821474232313712noreply@blogger.com