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  • MartinD_CZ commented on MartinD_CZ's instructable Lithium Battery Utility Board8 weeks ago
    Lithium Battery Utility Board

    Hi,interesting point. However, you are not taking into account the body diode - if you never apply 5V, the diode will still keep the source at roughly Vbat and since gate will be grounded, Q1 will be conducting. So that should work OK. And in the testing, I had no problems with that...I cannot tell you from memory which part I used (and I do not have any on hand), but I do believe I wrote it somewhere in the comments here...

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  • MartinD_CZ commented on MartinD_CZ's instructable How to Make Universal Battery Charger2 months ago
    How to Make Universal Battery Charger

    Hi,well, modifying it for 18V NiCd batteries won't be complicated. Regarding the V2 - well, I had to pause it because of other projects I had been working on, so now it is on hold. But since many people are asking me about it, I will try to finish it sometime. The problem is that I cannot (and don't want to) promise any finish dates, as I really do not know when I will get back to it...

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  • Wireless Serial (UART) for Arduino/STM32/etc.

    Hi,so basically you want the two Arduinos to communicate with each other, right?

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  • MartinD_CZ's instructable Wireless Serial (UART) for Arduino/STM32/etc.'s weekly stats: 3 months ago
    • Wireless Serial (UART) for Arduino/STM32/etc.
      1,200 views
      44 favorites
      2 comments
  • MartinD_CZ commented on MartinD_CZ's instructable Lithium Battery Utility Board4 months ago
    Lithium Battery Utility Board

    Hi,firstly, thanks for your feedback. Regarding your question - that is honestly hard to tell. I would say that they should not interfere during normal operation, but the real question is what would happen if for example both of them enter the undervoltage lockout mode. What I suggest is that you have the boards made with footprints for the protection, and then you do not populate the protection parts (that is R4, R5, U2 and U3). Then you just need to short all of the pins of the U2 footprint to complete the current path and voila - you have a board without protection...

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  • MartinD_CZ commented on MartinD_CZ's instructable Lithium Battery Utility Board4 months ago
    Lithium Battery Utility Board

    I sent you an email.

    Hi,my gerbers were optimized for AllPCB, but I see that OSHpark requires different format. I used the CAM tool from their official GitHub. You can find the Gerbers here, but I can not guarantee anything! Please let me know if they work, if they do, I will put it on my GitHub.

    Hi,you would need to provide a galvanically isolated 5V input for each cell, and even then it would not be a good solution... but I am building a project which will be able to achieve that, so stay tuned, I want to publish it in like two weeks....

    Actually, that's the thing I am working on right now :) It should be out in a week or two...

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  • MartinD_CZ commented on MartinD_CZ's instructable Lithium Battery Utility Board4 months ago
    Lithium Battery Utility Board

    thanks, I appreciate that!

    Hi,it's kind of hard to explain, so I made a picture, see below:

    Hi, thanks! :)Regarding your feedback: the B340A has indeed a leakage current of about 0.5 mA. But this leakage current then needs to go through the 10k resistor and it flows only when the circuit is switched on. And the MT3608 will consume much more current when switched on, so I considered that an acceptable loss...But you are right with the C4, it could have been closer, but I ran out of board space :)Anyways, thanks for you feedback!

    thank you too, I sent you an email...

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  • MartinD_CZ commented on MartinD_CZ's instructable Lithium Battery Utility Board4 months ago
    Lithium Battery Utility Board

    Hi,it can be available somewhere, I am not claiming this is something super new or innovative. I just needed a few of these boards for myself and decided to publish them afterwards, thinking they might be useful to someone...

    Well, thanks for the idea, but this is just a side project of mine, so I do not want to go through all the bother of putting it on kickstarter etc....

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  • MartinD_CZ's instructable Lithium Battery Utility Board's weekly stats: 4 months ago
    • Lithium Battery Utility Board
      1,455 views
      46 favorites
      10 comments
  • MartinD_CZ commented on MartinD_CZ's instructable Lithium Battery Utility Board4 months ago
    Lithium Battery Utility Board

    Hi,by that sentence I meant just the PCBs, having them populated would cost a lot of money on such a low scale. You can populate them yourselves, it takes about 20 minutes each, and you don't need much skill, the components are big enough for hand soldering.For beefing it up you would need to:A.) increase the output current - the MT3608 should handle up to 4 A, so in this scenario it should be sufficient for 5 V 2 A output. You would need to upgrade the inductor, diodes (SS54 would do) and capacitorsB.) change or disable the overcurrent protection featureC.) 2 A charging is actually the hardest part. You would need different IC, see for example http://cds.linear.com/docs/en/solutions-manual/Linear-Battery-Charger-Brochure-2016.pdfHope this helps a little bit...

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  • MartinD_CZ commented on MartinD_CZ's instructable Lithium Battery Utility Board4 months ago
    Lithium Battery Utility Board

    Hi, thanks. Actually, I thought about selling them for a brief moment, but the thing is that I would have to assemble them by hand, which takes a lot of time and it is a very boring job. And anyways, I made them primarily for myself, not to make money. But if you want, I can post you the PCBs (but hey, you can have them made in China for a few dollars) Regarding the beefed up version - that wouldn't be hard, but I do not have a use for such a beefed up version right now..

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  • MartinD_CZ commented on MartinD_CZ's instructable Lithium Battery Utility Board4 months ago
    Lithium Battery Utility Board

    Hi, yes, unfortunately you have to manufacture it yourself. Maybe I could post some of the PCBs to you, as I have about a 100 of them, but they will not be populated with components...

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  • MartinD_CZ commented on MartinD_CZ's instructable Lithium Battery Utility Board4 months ago
    Lithium Battery Utility Board

    No, you can order it from anywhere you want. Just download the zip file and there are either gerbers or eagle source files...

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  • MartinD_CZ commented on MartinD_CZ's instructable How to Make Universal Battery Charger7 months ago
    How to Make Universal Battery Charger

    Hi,yes, it indeed is, but most reference designs do not have a display and controls, they regulate based on some predefined values. In those applications you need the processor to react to a sudden change in the output ASAP, which is hard, when it is busy drawing the display or checking controls and doing a lot of other stuff. So yes, the method itself is okay. And the processor is still fast enough, I just wanted to point out that this is fine for battery charging, where the load changes slowly, but not for a lab bench power supply or something similar.

    UPDATE: I am currently working on version 2 of this thing, with cell balancing, better UI and lots of other stuff. Also it will be in a form of an Arduino shield. V2 should be out in October, so insted of building this, I recommend waiting for V2.

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  • How to Make Universal Battery Charger

    They do have the same potential indeed, but separating grounds is very common. There are two basic reasons - ground loops and noise. I am not honestly going to explain them, you can search for that very easily.

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  • How to make universal battery charger

    Hi,unfortunately, I do not have any layout files, as I have build this on a piece of perfboard... And you can work out the partlist from the schematics. I am planning version 2.0 with cell balancing, so maybe there I will provide layout & partlist

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  • MartinD_CZ's instructable Arduino-controlled True Switching Regulators's weekly stats: 1 year ago
    • Arduino-controlled True Switching Regulators
      9,261 views
      136 favorites
      25 comments
  • Arduino-controlled True Switching Regulators

    Well, you would need to use 2 MOSFETs then, and somehow control them. I fear TL494 cannot really do this, or I do not know about it. You could use 2 TL494, this could be possible, but why dont use the flyback inverting one? The only downside I can think about is its lower efficiency...

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  • Arduino-controlled True Switching Regulators

    You mean like isolated? Because there is already a schematic for inverting converter, which can be called "universal"....

    Eagle, https://cadsoft.io/

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  • Arduino-controlled True Switching Regulators

    Hi, thanks. Well, when you look at almost any generic step-down converter (whether it is TL494, UC384x or LM257x based), they all use the same layout with only a few modifications. They always feed the output into some sort of error amplifier, sometimes with exposed negative input, sometimes not. They are all build this way, even the commercial ones. And they all work. I have been researching this for like 2 weeks, and the generic design is nothing unknown, it is all over the internet. My biggest contribution is the Arduino-control part.But for the sake of both of us, lets end this. Nobody else complained about anything, and I (and you too, I think) do not want to spend my time writing what was already written.

    Yeah, this came to my mind too, but I thought it would make the whole build more complicated and harder to understand....And using N-MOSFET is a very good idea, they how lower rds on and even more, I think they more common and thus easier to get. Thanks.

    I have sent you a PM

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  • Arduino-controlled True Switching Regulators

    Hi,firstly, it works - I have build it onto a breadboard and then as a standalone shield. If you do not believe me, do not believe me - that is your problem. However, look at my other Instructables, I am not some newbie. As for your arguments:1. loop compensation is done by two error amplifiers, they are connected to the voltage output and the current shunt. They get their reference from the RC filters, that come out of the PWM pins. The only reason it is also connected to the Arduino is that I display the output values into Serial Monitor. All the compensation is done by the TL494 (that is why I think this is better than connecting the whole thing directly to an Arduino)2. sticking a 1Meg resistor at the comp pin is OK. The datasheet states, that it should not be left floating, but it ...

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    Hi,firstly, it works - I have build it onto a breadboard and then as a standalone shield. If you do not believe me, do not believe me - that is your problem. However, look at my other Instructables, I am not some newbie. As for your arguments:1. loop compensation is done by two error amplifiers, they are connected to the voltage output and the current shunt. They get their reference from the RC filters, that come out of the PWM pins. The only reason it is also connected to the Arduino is that I display the output values into Serial Monitor. All the compensation is done by the TL494 (that is why I think this is better than connecting the whole thing directly to an Arduino)2. sticking a 1Meg resistor at the comp pin is OK. The datasheet states, that it should not be left floating, but it also should be protected against false triggering. So a resistor with high enough value is used (I have seen this in many designs) - it does not matter if it is 820K or 1M, I wanted to help the potential builders in telling them which values are not that critical.3. I do not provide a code because outputting PWM from Arduino is so simple that if you cannot do it, you are probably not able enough to build this.Honestly, I am very disgusted by your comments. Some notes I would like you to read:1. Instructables has "be nice" comment policy. You firstly accuse me and than call this a fake (or I do not know how to call it) without waiting for my reply. This can discourage other people from posting on Instructables!2. I bet you havent even read the whole Instructable or the TL494 datasheet. You just looked at the schematics and made your opinion.3. When I look onto your profile, you accused a lot of other Instructables this way. So everybody else is stupid and your are the smartest person on planet Earth, right?3. You asked a very good question - why would I post something which does not work? I have posted 3 other Instructables, all of them working fine. I do this in my free time. I do not have anything from it apart from good feeling (yeah, I have joined a contest, I have like zero chance of winning). I thought the idea is worth a share, so I have written this.Overall, if you are a man, you should apologize for the way you have accused me. I am OK with a discussion - tell me what would you improve, and I will think about it. Otherwise, I am not going to spend my time replying to your rude comments.have a nice day John.

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  • How to make universal battery charger

    Well, to receive data from UART, you need an UART to USB converter (2 USD on Ebay). Discharging FET is any generic FET in TO-220 mounted onto a heatsink. The ISP is something different from UART.

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  • How to make universal battery charger

    Hi,Unfortunately, I do not have a partlist, since anybody can customize their project. But I provided schematics, so I hope you can write down the parts really easily. Getting the parts - either Ebay or your local RadioShack, depends on your local prices & delivery times from Ebay

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  • How to make universal battery charger

    yeah, I used those

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  • How to make universal battery charger

    Q1 is a general NPN tranzistor. Q2 is a P-channel MOSFET. IRF9540 should work fine.

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  • How to make universal battery charger

    sure I will help, just drop me a message or write in the comments :)

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  • MartinD_CZ commented on MartinD_CZ's instructable Simple AVR Laser Game Gun1 year ago
    Simple AVR Laser Game Gun

    Hi,the code is compatible with Arduino, if you copy-paste it into Arduino IDE it should work. Working with ATtiny boards is possible, it would require just a simple modification.

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  • MartinD_CZ commented on MartinD_CZ's instructable Simple AVR Laser Game Gun1 year ago
    Simple AVR Laser Game Gun

    Hi,I used 1 lithium battery (3,7 V) per gun and 5 V boost converter to boost it up to 5 V. However, you can do without the boost converter...

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