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How do I supercapacitor (was What Kind of Connector is This?
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How do I supercapacitor (was What Kind of Connector is This?

by crono141 on Mon Dec 12, 2016 12:01 am

I have a 4 pin connector on an existing piece of equipment (Old LCD TV) that I'm trying to connect to. Problem is I have no idea what this connector is called in order to purchase the mating plug that would go in it. Can anybody help me identify this connector?

Image

Its the 4 pin connector right next to the screw. It carries 12v on the two pins on the right and ground on the 2 pins on the left
Last edited by crono141 on Mon Jan 02, 2017 11:22 pm, edited 1 time in total.

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Re: What Kind of Connector is This?

by zener on Mon Dec 12, 2016 1:00 am

I would say it is made by JST. These are sold many places including Digi-Key. Measure the exact pin to pin spacing then search on Digikey.

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Re: What Kind of Connector is This?

by adafruit_support_mike on Mon Dec 12, 2016 3:38 am

Using the most general terms, it's a 'shrouded, keyed, rectangular connector'.

Unfortunately, connectors are one of the places where hardware manufacturers play the 'standard, but not standard enough to be helpful' game. There are about a million different pieces of hardware that connect four pins to four wires, all with minor differences in shape and dimensions.

If you can find a service manual for the TV, you might be able to get a manufacturer and part number. If not, you'll have to start narrowing things down by dimensions.

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Re: What Kind of Connector is This?

by zener on Mon Dec 12, 2016 4:24 am

If the spacing is 2mm then maybe this:

http://www.jst-mfg.com/product/pdf/eng/ePH.pdf

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Re: What Kind of Connector is This?

by crono141 on Mon Dec 12, 2016 9:24 am

Thanks, all. Dimensionally it is approx 9.5mm wide (outside), 4.75mm tall, approx 7mm deep, and the gap is 4mm wide. Spacing is 2mm between pins.

Image

Looks like a JST-PHR-4 plug will fit it. Does adafruit sell kits for this plug?

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Re: What Kind of Connector is This?

by adafruit_support_bill on Mon Dec 12, 2016 9:50 am

We don't stock those. You can probably find it at Mouser or DigiKey.

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Re: What Kind of Connector is This?

by Keebie81 on Mon Dec 12, 2016 3:06 pm

I have also found Digikey tech support very helpful when trying to identify a connector or choose from the list of multiple variations. Give them a call and they can help you through choosing one.

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Re: What Kind of Connector is This?

by crono141 on Sun Jan 01, 2017 11:13 pm

zener wrote:If the spacing is 2mm then maybe this:

http://www.jst-mfg.com/product/pdf/eng/ePH.pdf


Thanks everybody. Thanks to the above PDF, I determined that the mating plug was a PHR4. I was able to order this from digi-key, along with the needed internal pin connectors. Unfortunately, the crimping tool was something like 1500 dollars, so I had to settle with using pliers. Suffice to say, I got it to work. I'm currently in the process of cataloging my project on my blog at https://specterindustries.blogspot.com/, if anyone is interested in where this went. Thanks again.

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Re: What Kind of Connector is This?

by adafruit_support_bill on Mon Jan 02, 2017 7:47 am

Nice work! Thanks for the follow-up.

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Re: What Kind of Connector is This?

by crono141 on Mon Jan 02, 2017 2:53 pm

OK, everyone. I'm moving into the final phase of my project. The last hurdle I need to jump is that the way the Pi is connected to the above power supply means that when the TV is turned off, the power is immediately cut. This does not allow for a clean shutdown, and from what I've been hearing a Pi SD card will only survive to many such shutdowns before filesystem corrupts.

So here's my plan. I've ordered one of those external cell phone charger batteries. I'm going to put it in line with my regular power supply so that when the power is cut at the source, the pi will still be running on battery. At the same time I want to install a 3.3v voltage regulator across my 12V source (in parallel with the 12v to 5v DC converter), and connect this to a GPIO input on the Pi, which I will watch with a python script. When the script senses this voltage going to zero, it will initiate a shutdown command. This will allow me to just hit the power button on the TV and get a safe shutdown every time. Here's the schematic:

Image

My question is: do I need a resistor in series on the GPIO pin to prevent frying the Pi? If so, how large? My circuits knowledge and experience is not very good when it comes to this sort of thing. Thanks!

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Re: What Kind of Connector is This?

by zener on Mon Jan 02, 2017 3:24 pm

I have seen that taken care of before with a supercap. If the grounds are common you can sense the external voltage directly with a voltage divider. Otherwise you could also use an optocoupler. Your way would work also. You might put a pull down resistor on the IO pin that the 3V regulator is connected to.

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Re: What Kind of Connector is This?

by crono141 on Mon Jan 02, 2017 3:57 pm

zener wrote:I have seen that taken care of before with a supercap. If the grounds are common you can sense the external voltage directly with a voltage divider. Otherwise you could also use an optocoupler. Your way would work also. You might put a pull down resistor on the IO pin that the 3V regulator is connected to.


That's what I'm wondering about. What size resistor should I use? And if I don't use a resistor, will I be in danger of damaging my hardware?

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Re: What Kind of Connector is This?

by zener on Mon Jan 02, 2017 4:14 pm

As long as the regulator never spikes above the max input voltage of the IO pin then you are OK. I would follow the datasheet recommendations for external capacitors (if any) and give it some load to work into like 1K. However I would just use a divider if the grounds are common.

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Re: What Kind of Connector is This?

by crono141 on Mon Jan 02, 2017 4:33 pm

OK, thanks.

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Re: What Kind of Connector is This?

by zener on Mon Jan 02, 2017 4:57 pm

But yes, a series resistor would be good also. You would put the pull down on the regulator side of the series resistor.

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