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User Help Web Pro

Best technologies to create this media hosting service?

I’m sorry for this is not a general question, but a rather subjective one to my case. I’m an android developer in my profession and I need a web-related consultation. I’m building a small media hosting service that should contain several main functions: image, gif and short-video upload (simple like Imgur) have users. register by […]

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Ask Electrical Engineering Engineering

Ebike 24v relay board – switch?

Hi I’m building an Ebike and using a reclaimed relay board from an old electric moped. My question is the relay board has 3 small wires presumably for the switch, but this confuses me as I only need 2 for a switch. See picture: Also why use 8 relays. Extra info, 1500w hub motor, 2x12v […]

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Question of possible circuit

Suppose we have an alternating signal and another signal is produced in the loop which is DC. Is there a circuit which tracks down the DC signal even if it is mixed with an AC signal?(somehow removes the AC signal from its output) I am asking this question to find it so I can begin […]

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Doubt regarding inductors and transformers

If inductors block AC then how come transformers work only on AC? Please clear my concept.

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Ask Electrical Engineering Engineering

Possible to control a transistor by BC terminals?

I’m thinking about a strange working mode: the CB part is forward biased and trying to control EC current by CB current. EB is reversed. May it work? Transistor is BJT.

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Ask Electrical Engineering Engineering

Determining current through LED light

Not an electrical expert so please bear with me. I bought a no-name brand LED lamp that I would like to use with my 9V DC adapter as power source. The lamp uses 3 AA batteries in series. Batteries supplied with the lamp are HDX brand and I found their specification via the seller’s site. […]

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Can similar inductor value be used?

I found a schematic online of a 433mhz receiver which I am trying to replicate. 1 component is an inductor 16.6nh smd. However because I cannot find that exact value I was thinking to use an inductor with similar value 16nh. Would it work or not?

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Arduino Ask Engineering

ST7789 TFT display only shows a correct image while Arduino reset button is held down – Why?

I am trying to get the ST7789 TFT display to work with Arduino. I followed online guides for connections and am using the fast library fron github and included workbench ino (https://github.com/cbm80amiga/Arduino_ST7789_Fast). Problem: The program runs and drives the display but the image is corrupt and only partial. I discovered that if I quickly and […]

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Cryptocurrency Ethereum Mastering Development

payable and unpayable functions in solidity

I’m making a board game using solidity. I start the game with some fee, play the game, and give the hosting fee to the winner. So I made a contract like this: contract BoardGame { Player p1; Player p2; uint256[] board; uint fee = 1 ether; function startGame(Player _p1, Player _p2, unit256[] _board) external payable […]

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Mastering Development

Overlaying two contour plots in one plot?

I have a problem with overlaying two contour plots in one plot? I used the following script. # contour plots contour1<- ggplot(data, aes(x=data$cond1, y=data$cond2), col="red" )+ geom_density_2d() contour2<- ggplot(data.2, aes(x=data.2$cond1, y=data.2$cond2) )+ geom_density_2d() # Normalizing some points for adding to the cantour plots xa <-(test1$1 – minX)/(maxX – minX) ya <-(test2$1 – minY)/(maxY – minY) […]