Is anyone making a std , centre -ve 9vdc to a 5v dc usb female socket lead?

JMP220478

Need to power a usb wireless host on a pedalboard - want to avoid any std usb charger units n utilise 9vdc from current ( sorry couldn’t resist) power supply . 

Seen a number of 5v usb to 9v step up leads .. 

cheers for looking n constructive feedback 

PrecisionGuided

Typing  usb 5v to 9v converter guitar   into Amazon's search box comes up with a few

Obvs check they are centre neg - not all of them say...

The Hincore one is out of stock

DV247 do one  Fame EVC-1 Power Converter USB to 9V favorable buying at our shop (dv247.com)

ecc83

Problem is you need to get the right sized DC co ax plug. I would buy the right plugs and a £1 USB 2.0 cable and get slodderin!

Dave.

JMP220478

PrecisionGuided said:

Typing  usb 5v to 9v converter guitar   into Amazon's search box comes up with a few

Obvs check they are centre neg - not all of them say...

The Hincore one is out of stock

DV247 do one  Fame EVC-1 Power Converter USB to 9V favorable buying at our shop (dv247.com)

Cheers but I don’t need a step up from 5vdc usb to 9vdc centre -ve barrel - I need to other way round step down from a voodoo or strymon 9v outlet to a 5vdc usb female 

JMP220478

ecc83 said:

Problem is you need to get the right sized DC co ax plug. I would buy the right plugs and a £1 USB 2.0 cable and get slodderin!

Dave.

9vdc 5.5mm by 2.1mm barrel connector centre -ve ====>  ( step down ? ) =====> 5v dc usb 2.0 female connector 

I can solder but how do I drop the voltage to avoid cooking a usb device plugged into the female connector ?

Danny1969

Easiest way is Use a 7805 linear regulator  ...  

This will work fine from 7V to 15V 


 
Use a TO-220 package 7805 regulator. The heat created will be the voltage drop X the current drawn so 4V X whatever the current draw will be. 

ecc83

Might I suggest the R and LED be moved to the 5V side? The 78 regulators can sometimes go a bit 'loopy' without a small load on them. And I don't know how old that circuit is but a modern LED running at ~10mA will be blinding! 1mA will probably be fine. I have had 'lucky bag' LEDs perfectly usable at 200 micro amps!

Dave.

JMP220478

Just doing a little net based research

Is a simple voltage divider not an option here ? 

digitalscream

Or...you can get one of the many pedalboard power supplies that have a USB socket built in for exactly this purpose.

The problem with doing it the way you want is that a pedalboard power supply usually won't be able to provide anywhere near the current required by some USB devices. Depending on your power supply, it could be as low as 9V @ 100mA, or 5V @ 180mA, whereas even the USB 2.0 spec allows devices to draw up to 5V/500mA.

Wireless devices can be notoriously power-hungry, so...exactly what are you trying to power? They also often introduce a lot of noise into the power supply, so you'd need a properly-isolated supply for it to be usable.

Danny1969

No, because it won't hold the 5V steady with a varying load. The regulator will and only cost about 90 pence so it's pointless not using one. 
Internally the regulator does operate as a voltage divider but it uses a transistor as a constantly active variable resistor to keep the voltage balanced with the load. 

You can omit the LED and it's resistor leaving you with one regulator and 2 caps.  

Or you can get a small PCB board that uses a buck convertor, these tend to have the USB socket on them already but may inject a bit of noise into the mix so I generally use linear regulators for small current draws. 

If you want one of those then 

https://www.ebay.co.uk/itm/193727621572

Remember to get the pos and neg the right way round on the input, either cut and cross over the cables or get a cable already reversed on end to negate the dumb pedal power being neg centre 

JMP220478

@digitalscream ;

https://www.aliexpress.com/item/1005004946006873.html

the small usb component in the listing - effectively a wireless mini usb host that needs power but doesn’t power device it is attached to 

digitalscream

Yeah, they haven't provided any specs for it, which is a little frustrating. As an alternative to this, you could always just power it from a USB power bank?

JMP220478

digitalscream said:

Yeah, they haven't provided any specs for it, which is a little frustrating. As an alternative to this, you could always just power it from a USB power bank?

I did consider latter - I’ll try one of the voltage drop circuits n order one of these too https://www.ebay.co.uk/itm/295900295885?itmmeta=01HRQP2A6TAJ7RV3QEMPHKM542&hash=item44e50832cd:g:ZUsAAOSw3~BkqFYI

just want a neat solution - I can’t imagine the current draw will be excessive .

I do have a virtual battery n also a voodoo lab ps with a sag feature but ideally want to power everything from a strymon zuma