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Everything posted by HarryA
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You points are well made; thanks. On day one I found two voltage boosters on Ebay that gave more than 100 volts so I ordered both of them from China. The first one I received was a 12v dc to 200 v dc. After connecting it up and adjusting it for 200 v I put a 100k resistor across the output and got 2 volts output! It took a one mega-ohm load to keep 200 v. The second one (12v dc to 220 v ac) works well. I connected it to the 220v to 120v step down transformer and into a full wave bridge rectifier with a 100mfd capacitor and got 140 v dc; 9.6 volts input. With a 8.4 v NiMH rechargeable battery I get 128 v dc. So I am happy with that and very surprised that the 50/60 hertz transformer works at all!
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Hello from cold and snowy NE PA, In my quest to convert 9 - 12 volts dc into 140 volts dc I purchased a "40W DC-AC 12V To 220V Step-up Transformer Boost Module Inverter" via Ebay. I also purchased a 220 volt to 120 volt 50-60 hertz step down transformer; the type travelers use. But the inverter's output is 38.4k hertz! So my transformer is useless here. I am wondering if one can find a transformer that will handle that frequency and is two to one? I am driving a class D pulse amplifier that outputs 100 Volts peak at a current of 0.10 amperes max. The pulse is 0.4 ms duration at and interval of 2 ms. So I am thinking that I need: 100v * 0.10 * 0.4/2 = 2.0 watts for the amplifier output so I am thinking about 10 watts for the amplifier and the conversion from 120 ac to 140 dc. "
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100V 10A constant charging current circuit ?
HarryA replied to vanbutan's topic in Electronics chit chat
It maybe cheaper to buy one? http://www.ebay.com/itm/1200W-100V-DC-Switching-power-supply-for-LED-Strip-light-AC-to-DC-power-supply-/182370960410?hash=item2a7628041a:g:sukAAOSw6aVUn95M -
Is there some way to get read of the %^^*)(*^ pop up with " would you like to receive notifications.... ? I DO NOT WANT ANY!
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You could charge the cap. with solar cells during the day and light an LED at night? No batteries required! see: http://www.ebay.com/itm/Maxwell-D-Cell-Power-350F-350-F-Farad-2-7V-Super-Capacitor-Cap-Ultra-Battery/281173041415?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D888007%26algo%3DDISC.MBE%26ao%3D1%26asc%3D38530%26meid%3D4d48fa267f404223bb70c8c93e334efc%26pid%3D100009%26rk%3D1%26rkt%3D1%26sd%3D161240113620 man that is some url!
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Most likely you have a few screws loose John see: http://en.allexperts.com/q/Electrical-Wiring-Home-1734/2009/6/Circuit-reads-60-volts.htm also search on: "electrical problem 60 volts on 120" good luck. addendum: As this a common problem could a poor connection between copper (or better yet corroded copper; copper oxide) and plated steel act as a diode and the the results (at very low current) is a half wave rectifier? That would yield the 60 volts rms. ref: http://www.tutorvista.com/physics/half-wave-rectifier-calculation
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Thanks for the reply. I have a a 400 microsecond pulse every 20 ms that I wish to amplify. I need about 100 volts so I an thinking I need a 150-200v transistor. I need to preserve the varying amplitude so I can not just emulate it with a switching transistor. Speaking of transformers; I tried amplifying it with a 2n7000 n channel MOSFET using an audio transformer in reverse (input into the 8 ohm windings ) but I could not get a decent output pulse in spite of using various combination of diodes. HarryA \../ To close this out. I found mouser.com to be helpful as they have a system of filters that makes it easier to find what you want - with some effort. I ordered the n-channel ZVNL120 eMOSFETs from then; 200v and 120ma. The book "Electronic Devices and Circuits" by "Schaum's easy outlines" has good information on circuit design using bipolar, FETs, and MOSETs tranistors.
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Hello from NE PA, Where do you all find data on MOSFET transistors? I look on ebay for MOSFETs but most do not have specs so you have to search for a data sheet, download it, open it, and find it's not what you want! I am looking for an n channel eMOSFET for a class D amplifier that has 150 to 200 volt drain to source. Some 20 to 40 ma for current. I find lots of power switching MOSFETs references. Are there any good books on using MOSFET transistors? thanks in advance, HarryA
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Hello from NE PA, A question for you. How to TENS machines generate 40 to 60 volts from say 4.2 volts without using a coil or transformer? Pictured is a TENS circuit that is about 1.26 inches by 1 inch. The battery is on the reverse side of the board. thanks in advance, HarryA
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I picked up some LM317's today (1.5 amperes max.). Set the output to 7.0 volts and connected to a brushed motor. The motor drew 0.68 amperes. The output voltage dropped to 6.86 volts; the li-po battery output drop to 11.55 from 11.80 volts. This is with no load on the motor; I need to get propeller on it. Someday I will receive the ESC and can reverse the motor on the fly. :)
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Thanks. I replaced my diagram with the one from Motorola before seeing yours. I have power transistors coming from my favorite store - ebay. ;)
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My "bright" idea is to use the mosfet to get more than the 1 ampere that the 8 volt regulator is rated at. I have a large 11.1v li-po battery for the main motor so I don't want to add another battery to get the 8 volts. I wonder if one can put two or three regulators in parallel for more current? This current is the power supply for the speed controller; it connects to the receiver for the PWM. It is the brushed type used with rc cars so it can reverse the motor for left and right control.
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Hello all, I need to connect an 8 volt electronic speed control to an 11.1 battery. I have an 8 volt regulator and a power mosfet. I have not worked with mosfets before so I am puzzled on how to make the connections and what values of resistors are required. Please take a look at my diagram. Any advice would be appreciated. This motor control is for the stern of a model blimp to control the direction much like a helicopter's directional control. see:
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Thanks guys. That's what I needed to know :) I made a tester out off a 12 v brake light and a 6 volt one ;)
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I have a new power supply that I would like to check before installing into the computer. On bench testing it I get no voltage at all. Is thid correct? I am thinking that perhaps there is some type of interlock so you only get voltage when it is installed? thanks in advance.