Shortening a 5v cable.

[Nigella Bryant]

Hi can this cable be shortened to 30cm without affecting the resisters inside?

[scotty38]

Yep, I did just that to one of mine. Just make sure to observe the polarity and make sure you rewire it the same as it started out.

 

Edit what resistors and this is a 12v cable isn't it, not that it makes a lot of difference to the shortening question?

Edited November 2, 2021 by scotty38

[whipdry]

LED resistor? 

[Alan White]

Hi Nigella, 
5v cable? thats a 12v plug on the cable shown??
Yes the one shown can be shortened.

[scotty38]

17 minutes ago, whipdry said:

LED resistor? 

Yep if there's an led no doubt there's a current limiter too so yeah keep that in circuit

[Jonk]

These cigar lighter plugs tend to have a fuse in - the LED / resistor combo will not be a current limiter, is is purely there to show it's powered up. The resistor current limits the LED so only 3Vdc or is across the led, for around 15mA.

You can reduce the length no problem, but I would ask why do you need to do this? If you're going to go to the trouble of modifying the cable, then get rid of the cigar lighter plug / socket and use something more substantial (if you can).

[Nigella Bryant]

Hi all and thanks for the replies. I've the hitecastro electronic focusing unit and it came with a cigar connection and then to USB, nuts I know. Could I get a suitable use to the input, never seen that type before. I've run it with the female cigar USB before but with the new mount all cabling is internal to the USBs on the mount. I wanted to shorten the cable so I don't have spaghetti trailing everywhere again which undermines the whole thing of internal cabling/USB hub on the mount. Not good pics just downloaded of net for quick response, lol. 

[Jonk]

A USB connection is typically required to use less than 500mA (the limit for a USB 2 output on a PC for example).

Some phone chargers can be up to 2.5A at 5Vdc, but in your case, how much current does the device need? It may show in power rather than current on the label, so 5V x 0.5A = 2.5W maximum. If it's lower than 2.5W, then a normal USB output should suffice (as long as it's not a shared output with other sockets - for example on a laptop, 2 usb outputs may share the same bus and therefore the total power capacity.

A quick look at one of these devices shows separate a usb and 12V connection, usb for the data, 12Vdc for the power, probably why you were provided with that cable.

 

[fifeskies]

 

Just to help clarify, as far as I understand it not having used this unit.

The focus controller is powered by 12v standard input

buttons on the unit allow you to drive the motor in or out

 

The USB connection is for PC control

 

from web

when connected to a PC via USB2.0 that HitecDCFocus comes into its own.  Our specially written software provides exquisite control over your focus motor.  The minutest of focus motion can be acheived by adjusting the parameters of our software to your needs.

 

 

Edited November 2, 2021 by fifeskies

[scotty38]

1 hour ago, Jonk said:

These cigar lighter plugs tend to have a fuse in - the LED / resistor combo will not be a current limiter, is is purely there to show it's powered up. The resistor current limits the LED so only 3Vdc or is across the led, for around 15mA.

 

Exactly what I said, it's a current limiter for the LED, nothing else....

[Jonk]

1 minute ago, scotty38 said:

Exactly what I said, it's a current limiter for the LED, nothing else....

I know, it was the way I read it. 🙂

[Nigella Bryant]

Yes, that's it, thanks. I do use it for computer control. 

[Jonk]

If you're using a computer, I assume you have either mains power available or a battery set up with outputs?

I would cut the cigar lighter plug off and keep the cable as a spare, and use either a dedicated 12Vdc 2A or 3A PSU for the focus controller or a fused cable from your battery setup.

If you're not sure, maybe post a photo of your setup and environment and people can chime in.