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 How can I reduce voltage - from 5V to 4V? | ||
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 09-21-2014, 02:46 PM | #1 (permalink) |
Registered Users Join Date: Oct 2012 |
Hello Straight up, I do not know much about electronics, beside some simple soldering for my project, I am using a Castle ESC/10, where the BEC output is 5.0V (at the lowest setting). I need to drop it down to 4volts, otherwise the tiny servos I am using will burn up since they are rated at 4.2V How can I do the voltage drop? Advice, link would be very much appreciated. Thank you in advance ... |
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| 09-21-2014, 02:57 PM | #2 (permalink) |
Registered Users Join Date: Jan 2011 |
You could use something like one of these, between the BEC output, and the servos (so install it between the BEC, and your FBL unit, or RX, depending on how your setup is wired): http://www.western-robotics.com/STVR_hp.html http://www.amain.com/Western-Robotic...FU9k7AodpUEAcg It would give you roughly a 0.8V voltage drop, getting you around where you need. If you want the voltage even lower, you could use two of these, connected in series, dropping by about 1.6V. Then raise the BEC voltage back up again, to hit your target voltage. These are just diodes, there is a voltage drop as you go across them. The voltage drop increases as the current increases. So if you measure 4.2V, for instance, with no load on the servos, the voltage they receive will be lower once they actually start drawing current though the diode. __________________ |
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| 09-21-2014, 03:04 PM | #3 (permalink) |
Banned User Join Date: Jan 2010 |
I have a couple of suggestions. Someone else might chime in and offer a better solution though, I'm no expert. https://www.dimensionengineering.com.../anyvolt-micro https://www.dimensionengineering.com/products/anyvolt3 Or something like this from ebay: http://www.ebay.com/itm/LM2596S-Step...item3a9203c3ac Check the specs on that anyvolt micro. It has a fairly low amp rating. Is this for an aircraft or something else? |
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| 09-21-2014, 03:09 PM | #4 (permalink) |
Registered Users Join Date: Nov 2013 Location: Aberdeen, UK |
From 5v to 4v (ish) all you need is a simple and cheap silicon diode. You will drop about 0.7v over a diode which is probably near enough? Just make sure the diode is rated for the power you need. __________________ |
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| 09-21-2014, 03:47 PM | #5 (permalink) |
Registered Users Thread Starter Join Date: Oct 2012 |
Thank you guys, very helpful ... but, i should explain a bit more. I am concerned with weight, i thought of the Align drop down ... but, a bit heavy. I was planning on using it on a 130x conversion process, wherein i would like to test a miniV instead of the stock 3n1 board. the servos for the 130x are rated at 4v, miniV can go down to 3.5v. i saw folks using rotary servos (which can do 5v), but i do not have any of those in hand and don't really want to incur additional expenses on a project. soldering diode as some suggested seem simple. any link on type of diode i should use, and do i solder the red or the black wire coming from the BEC to the miniV? i am guessing the red wire. time for a trip to Radio Shack |
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| 09-21-2014, 04:12 PM | #6 (permalink) |
Registered Users Join Date: Nov 2013 Location: Aberdeen, UK |
A '1N4001' silicon diode will do the job if the current is up to 1A. They have a white stripe around one end, the stripe goes to the negative side of the circuit. __________________ |
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| 09-21-2014, 04:21 PM | #7 (permalink) |
Registered Users Join Date: Nov 2013 Location: Aberdeen, UK |
PS.. if you need more current a 1N5400 will do 3A __________________ |
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| 09-21-2014, 04:26 PM | #8 (permalink) |
Registered Users Thread Starter Join Date: Oct 2012 |
Quote: Originally Posted by Grumpy_Old_Man A '1N4001' silicon diode will do the job if the current is up to 1A. They have a white stripe around one end, the stripe goes to the negative side of the circuit. Thank you again, i found a diode ... please see attached. My two guesses, are they correct? 1. Diode should be soldered only to the RED wire. Black/Signal wires gets plugged directly into the RX/miniV 2. how about the direction of the diode, is it correct (please refer to photo)? Thank you .. Khan |
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| 09-21-2014, 04:35 PM | #9 (permalink) |
Registered Users Join Date: Nov 2013 Location: Aberdeen, UK |
Yes, put it in the red wire, but you have it the wrong way around. The white stripe needs to face the negative side of the circuit, i.e. it should face away from the positive supply from the BEC. __________________ |
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| 09-21-2014, 04:47 PM | #10 (permalink) |
Registered Users Join Date: Jan 2011 |
You're using very-small servos, and your BEC is likely fairly-powerful, in the context of a 130X. But with a Mini VBar, I'd check for brownouts on the bench before flying. Move the collective up/down as fast as you can for maybe a minute, and watch for any odd behavior, and/or check the error log for low-voltage warnings. I was getting MiniV brownouts on my 450, when running at 6V. If starting as low as ~4V, you're a lot closer to the roughly 3.5V where the MiniV (and satellites) may start browning out. Granted, an unexpected crash on a 130X is not as disastrous as with a 700, but we all like to avoid crashes where we can. __________________ |
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| 09-21-2014, 09:20 PM | #11 (permalink) |
Registered Users Thread Starter Join Date: Oct 2012 |
Quote: Originally Posted by RedOctobyr You're using very-small servos, and your BEC is likely fairly-powerful, in the context of a 130X. . thank you for your post, i know exactly what you are talking about. i had the same issue with my 450, using miniV and DS95 servos. the servos were drawing too much and would cause brownouts. i was using castle Edge 50 lite, voltage set at 6v. i was lucky, the heli never crashed, but a friend of mine did crash. we bench tested the helis and noticed that the servos would act weird every now and then i ended up using an external BEC and disconnected the Castle's built in BEC. the problem went away |
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| 09-21-2014, 09:36 PM | #12 (permalink) |
Registered Users
Join Date: Apr 2013 |
Quote: Originally Posted by Grumpy_Old_Man A '1N4001' silicon diode will do the job if the current is up to 1A. They have a white stripe around one end, the stripe goes to the negative side of the circuit. Now tell me if i'm wrong, but don't you mean a resistor? Resistors act to drop current and voltage. Diodes work as a regulator of current flow like a check valve. This thread is the first time i have ever heard of anyone using a diode to drop voltage. diodes don't work like that. __________________ |
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| 09-21-2014, 10:33 PM | #13 (permalink) |
Registered Users Thread Starter Join Date: Oct 2012 |
So, I picked up a IN4001 Micromini Silicon Diode from Radio Shack. I hope I got the right one, the back states the following: Absolute Maximum Ratings (25 degree C) I can see the silver colored stripe on one end of the diode, which will be CLOSEST to RX/MiniV. The diodes come with kind of long wires on both ends, (1) can I shorten them? If shortening is not an option, (2) is it OK to bend them after soldering? Sorry for asking all these questions, but I just do not want to fry the miniV or the servos Thank you |
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| 09-21-2014, 10:39 PM | #14 (permalink) |
Registered Users Join Date: Oct 2013 |
Quote: Originally Posted by Frostwick Now tell me if i'm wrong, but don't you mean a resistor? Resistors act to drop current and voltage. Diodes work as a regulator of current flow like a check valve. This thread is the first time i have ever heard of anyone using a diode to drop voltage. diodes don't work like that. No. He means a diode. A diode has a relatively stable voltage drop across the p-n gate when forward biased (and reverse if we want to get technical). For a silicon diode it is fairly close to 0.7v when forward biased. A resistor is what is more commonly used as a current limiter. A diode can be used to protect against reversing current flow. That's your check valve but it is the most basic use of a diode. They are far more useful in other ways. To use resistors to drop voltage requires two and they have to be setup as a voltage divider. __________________ |
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| 09-21-2014, 10:41 PM | #15 (permalink) |
The Capi
Join Date: Oct 2006 |
Quote: Originally Posted by Frostwick Now tell me if i'm wrong, but don't you mean a resistor? Resistors act to drop current and voltage. Diodes work as a regulator of current flow like a check valve. This thread is the first time i have ever heard of anyone using a diode to drop voltage. diodes don't work like that. You have things alittle backwards, diodes do not regulate current, and they are commonly used for their voltage drop. Quote: Originally Posted by karma4u So, I picked up a IN4001 Micromini Silicon Diode from Radio Shack. I hope I got the right one, the back states the following: Absolute Maximum Ratings (25 degree C) I can see the silver colored stripe on one end of the diode, which will be CLOSEST to RX/MiniV. The diodes come with kind of long wires on both ends, (1) can I shorten them? If shortening is not an option, (2) is it OK to bend them after soldering? Sorry for asking all these questions, but I just do not want to fry the miniV or the servos Thank you You can always cut/shorten diode leads, you can also bend them. Just don't bend them too close to the package or it might damage it. __________________ |
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| 09-21-2014, 11:27 PM | #16 (permalink) |
Registered Users Thread Starter Join Date: Oct 2012 |
Quote: Originally Posted by karma4u Absolute Maximum Ratings (25 degree C) I just did a quick test with one of the diodes, hooked it up to my Jazz 40-6-18, which read 5.2V (without any load) - according to my 5 dollar Harbor Freight volt meter. I then checked with the diode to the RED wire, and it does drop the voltage .... but only to 4.86V. I was expecting a 1.6V drop (according to the OEM's specs) I guess, I will need to solder several of these diodes in series to get the 4.2V I need. cheers |
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| 09-22-2014, 02:54 AM | #17 (permalink) |
Registered Users Join Date: May 2012 |
Quote: Originally Posted by karma4u Hello Straight up, I do not know much about electronics, beside some simple soldering for my project, I am using a Castle ESC/10, where the BEC output is 5.0V (at the lowest setting). I need to drop it down to 4volts, otherwise the tiny servos I am using will burn up since they are rated at 4.2V How can I do the voltage drop? Advice, link would be very much appreciated. Thank you in advance ... Attend your classes. |
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| 09-22-2014, 03:23 AM | #18 (permalink) |
Registered Users Join Date: Nov 2013 Location: Aberdeen, UK |
The minimum voltage drop should be about 0.5-0.6v when there is any load at all. You are probably seeing less because you are measuring at zero load. Anyway, yes, you can connect a couple (or more) in series to increase the drop. __________________ |
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| 09-22-2014, 07:52 AM | #19 (permalink) |
Registered Users Join Date: Oct 2013 |
+1. What grumpy said. When something is open or acting as an open you will see source voltage when measuring across it. Plug something in that can handle the 5volts. A larger servo, a servo test, even just a 1k or larger resistor. You need some current flowing through the whole circuit to be able to measure the voltage. __________________ |
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| 09-22-2014, 08:08 AM | #20 (permalink) |
The Capi
Join Date: Oct 2006 |
Look at the I-V curve of the diode, he will never get 1.6V drop. A tail servo is only going to draw at most 1-2A, so the drop is likely to be alittle under 1V. __________________ |
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