On Tue, 16 Oct 2018 14:04:24 +0100, James Harris
<james.harris.1@gmail.com> wrote:

Having not touched any of this kind of stuff for years I'm looking to
power a small TTL test circuit which I intend to built on a breadboard.
I wondered if I could run it off USB power. In other words, is it
feasible to power a TTL cct via a USB lead and USB socket?

I found a "USB Mini B Breakout Board"

http://www.hobbytronics.co.uk/cables-connectors/usb-connectors/usb-minib-breakout

but I'm not sure that the PCB bit of it is necessary and, besides, it's
only rated for 100mA (which may be enough but I can't be sure at this
stage). If not USB, I guess I should go for a wall wart and a 7805.

So the question is whether there's a good way to power a circuit via
USB, or whether you think I should go down the wall-wart or some other
route.

Any suggestions?

I use the USB connector on my projects now even if they have no
connection to a PC. It gives the choice of a PC/Laptop or one of the
many cheap USB wall wart chargers or a car charger. The USB connector
is almost a standard but for home use the breakout board is convenient
as the holes are on 0.1" pictch so you can fit a header to plug it in
to a protoboard etc.

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On 17/10/2018 14:41, James Harris wrote:

On 16/10/2018 15:45, Geo wrote:

...

I use the USB connector on my projects now even if they have no
connection to a PC. It gives the choice of a PC/Laptop or one of the
many cheap USB wall wart chargers or a car charger. The USB connector
is almost a standard but for home use the breakout board is convenient
as the holes are on 0.1" pictch so you can fit a header to plug it in
to a protoboard etc.

That's good. If USB power is stable enough (and, if not, I guess I could
add smoothing) then it seems the most convenient option, what with
sources including mains, computer, car battery, portable power pack etc.

As for the connectors, which do you use. I've seen a USB-B receptacle
which might do

https://uk.farnell.com/amp-te-connectivity/1734517-1/usb-connector-2-0-type-b-rcpt/dp/2778492?st=usb%20pcb

Incidentally, there's currently a type-A socket at

https://www.ebay.co.uk/itm/3pcs-USB-surface-PCB-mount-socket-Female-Type-A-connector-right-angle-ref-674-/283186649635

and its pins look like they might be more conveniently laid out /if/
they have 0.1" spacing. Can you see any reason not to use a type-A
connector on a device? Devices are supposed to use type-B.


--
James Harris

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On 16/10/2018 15:45, Geo wrote:

On Tue, 16 Oct 2018 14:04:24 +0100, James Harris
<james.harris.1@gmail.com> wrote:

Having not touched any of this kind of stuff for years I'm looking to
power a small TTL test circuit which I intend to built on a breadboard.
I wondered if I could run it off USB power. In other words, is it
feasible to power a TTL cct via a USB lead and USB socket?

I found a "USB Mini B Breakout Board"

http://www.hobbytronics.co.uk/cables-connectors/usb-connectors/usb-minib-breakout

but I'm not sure that the PCB bit of it is necessary and, besides, it's
only rated for 100mA (which may be enough but I can't be sure at this
stage). If not USB, I guess I should go for a wall wart and a 7805.

So the question is whether there's a good way to power a circuit via
USB, or whether you think I should go down the wall-wart or some other
route.

Any suggestions?

I use the USB connector on my projects now even if they have no
connection to a PC. It gives the choice of a PC/Laptop or one of the
many cheap USB wall wart chargers or a car charger. The USB connector
is almost a standard but for home use the breakout board is convenient
as the holes are on 0.1" pictch so you can fit a header to plug it in
to a protoboard etc.

That's good. If USB power is stable enough (and, if not, I guess I could
add smoothing) then it seems the most convenient option, what with
sources including mains, computer, car battery, portable power pack etc.

As for the connectors, which do you use. I've seen a USB-B receptacle
which might do

https://uk.farnell.com/amp-te-connectivity/1734517-1/usb-connector-2-0-type-b-rcpt/dp/2778492?st=usb%20pcb


There's currently a better shot of the pins of a similar socket at

https://www.ebay.co.uk/itm/K1X4-10-Pcs-USB-Female-Type-B-Port-4-Pin-Right-Angle-PCB-DIP-Jack-Socket-V7S1/302801941235

Is that the connector you use or do you get enough current through a
Mini-B or Micro-B or something else?


--
James Harris

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On Wed, 17 Oct 2018 14:45:33 +0100, James Harris
<james.harris.1@gmail.com> wrote:

Incidentally, there's currently a type-A socket at

https://www.ebay.co.uk/itm/3pcs-USB-surface-PCB-mount-socket-Female-Type-A-connector-right-angle-ref-674-/283186649635

and its pins look like they might be more conveniently laid out /if/
they have 0.1" spacing. Can you see any reason not to use a type-A
connector on a device? Devices are supposed to use type-B.

Might be more difficult to find a suitable cable.
I have used a type B similar to the one you mentioned but horizontal
mounting. The 4 pins squeezed into a 0.1 pitch veroboard but the two
mouting holes had to be enlarged. Have also used the easier method
with the mini breakout and on one unit I just have a fixed cable with
type A at the end for power.

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