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Power a test TTL circuit from USB?

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James Harris
Guest

Tue Oct 16, 2018 2:45 pm   



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?


--
James Harris

Phil Hobbs
Guest

Tue Oct 16, 2018 7:45 pm   



On 10/16/18 9:04 AM, James Harris wrote:
Quote:
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?



Sure, that'll work. But why on earth use TTL in 2018?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

Jasen Betts
Guest

Tue Oct 16, 2018 8:45 pm   



On 2018-10-16, James Harris <james.harris.1_at_gmail.com> wrote:
Quote:
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.


They can only claim 100mA as that's all that USB guarantees without
some sort of complicated negotiation. in actual use It can probably do
500mA or more (not that soldeless breadboard is suited to currents
above about 200mA)

Quote:
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.


USB-shaped "phone chargers" that produce 5V at 500mA or more are
easily had.

--
Notsodium is mined on the banks of denial.

James Harris
Guest

Wed Oct 17, 2018 2:45 pm   



On 16/10/2018 19:37, Phil Hobbs wrote:
Quote:
On 10/16/18 9:04 AM, James Harris 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?



Sure, that'll work. But why on earth use TTL in 2018?


TTL, 0.1" through-mounts, and and bipolar transistors are all I know. I
told you I hadn't done this for years! What would you recommend 'these
days'?


--
James Harris

James Harris
Guest

Wed Oct 17, 2018 2:45 pm   



On 16/10/2018 20:21, Jasen Betts wrote:
Quote:
On 2018-10-16, James Harris <james.harris.1_at_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.

They can only claim 100mA as that's all that USB guarantees without
some sort of complicated negotiation. in actual use It can probably do
500mA or more (not that soldeless breadboard is suited to currents
above about 200mA)

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.

USB-shaped "phone chargers" that produce 5V at 500mA or more are
easily had.


I've been trying to work out USB power negotiation without much success.
I recognise that an un-negotiated port can draw 100mA and I know that a
device can negotiate for more. I am not clear, though, on whether
there's a cable or a particular outlet which will allow higher current
to an endpoint which doesn't do negotiation.


--
James Harris

Ralph Mowery
Guest

Wed Oct 17, 2018 3:45 pm   



In article <pq7dce$a9a$1_at_dont-email.me>, james.harris.1_at_gmail.com
says...
Quote:

Sure, that'll work. But why on earth use TTL in 2018?

TTL, 0.1" through-mounts, and and bipolar transistors are all I know. I
told you I hadn't done this for years! What would you recommend 'these
days'?




It all depends on what you are trying to do.

Check ou the Arduino. They are very small microprocessors so to speak.
You can get them from China off ebay for $ 2 or $ 3 each. Very simple
and easy to program from a computer. You can get a small PC board with
one on it and about 20 pin outs. Some can be used for analog input and
some for 0 or 5 volt output.

To program them you just plug in a cable from a computer USB port to the
port on the Arduino board. It will often power up the circuit too.

Check out Youtube for many things that can be done with them and a few
external components. Many programs are already out for them to do many
things.

Phil Hobbs
Guest

Wed Oct 17, 2018 6:45 pm   



On 10/17/18 9:27 AM, James Harris wrote:
Quote:
On 16/10/2018 19:37, Phil Hobbs wrote:
On 10/16/18 9:04 AM, James Harris 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?



Sure, that'll work.  But why on earth use TTL in 2018?

TTL, 0.1" through-mounts, and and bipolar transistors are all I know. I
told you I hadn't done this for years! What would you recommend 'these
days'?



HC for slowish stuff. TTL is vaguely similar but sucks power.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

Computer Nerd Kev
Guest

Wed Oct 17, 2018 11:45 pm   



In sci.electronics.components Phil Hobbs <pcdhSpamMeSenseless_at_electrooptical.net> wrote:
Quote:
On 10/17/18 9:27 AM, James Harris wrote:
On 16/10/2018 19:37, Phil Hobbs wrote:

Sure, that'll work.? But why on earth use TTL in 2018?

TTL, 0.1" through-mounts, and and bipolar transistors are all I know. I
told you I hadn't done this for years! What would you recommend 'these
days'?



HC for slowish stuff. TTL is vaguely similar but sucks power.


It seems to me that hardly matters unless you plan to run the final
device off battery power, or put one in every home. Admittedly the
100mA USB limit may be a factor if there are a decent number of
chips involved, but that's just one option for power.

--
__ __
#_ < |\| |< _#

Computer Nerd Kev
Guest

Wed Oct 17, 2018 11:45 pm   



In sci.electronics.components James Harris <james.harris.1_at_gmail.com> wrote:
Quote:
On 16/10/2018 20:21, Jasen Betts wrote:
On 2018-10-16, James Harris <james.harris.1_at_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.

They can only claim 100mA as that's all that USB guarantees without
some sort of complicated negotiation. in actual use It can probably do
500mA or more (not that soldeless breadboard is suited to currents
above about 200mA)

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.

USB-shaped "phone chargers" that produce 5V at 500mA or more are
easily had.

I've been trying to work out USB power negotiation without much success.
I recognise that an un-negotiated port can draw 100mA and I know that a
device can negotiate for more. I am not clear, though, on whether
there's a cable or a particular outlet which will allow higher current
to an endpoint which doesn't do negotiation.


100mA (or 150mA for USB 3) is the default limit that USB is _supposed_
to restrict devices to before they request more power. In practice this
is often omitted from computer motherboard designs to save cost, but
obviously they don't advertise this.

Many USB charger plug-packs don't restrict current, so they might be
easier as all you have to do is look at the current rating on the
sticker (sometimes this is only enough for the device it was
originally intended to be used with, rather than to conform to any
particular USB current limit).

Looking more boardly, there are lots of switch mode plug packs
without USB connectors, but which provide regulated 5V up to a
specified current, so they are an option too. Make sure they're
switch-mode, not transformer types (which I think you're already
aware of).

See "Low-power and high-power devices" here:
https://en.wikipedia.org/wiki/USB

--
__ __
#_ < |\| |< _#

Phil Hobbs
Guest

Fri Oct 19, 2018 2:45 am   



On 10/17/18 6:06 PM, Computer Nerd Kev wrote:
Quote:
In sci.electronics.components Phil Hobbs <pcdhSpamMeSenseless_at_electrooptical.net> wrote:
On 10/17/18 9:27 AM, James Harris wrote:
On 16/10/2018 19:37, Phil Hobbs wrote:

Sure, that'll work.? But why on earth use TTL in 2018?

TTL, 0.1" through-mounts, and and bipolar transistors are all I know. I
told you I hadn't done this for years! What would you recommend 'these
days'?



HC for slowish stuff. TTL is vaguely similar but sucks power.

It seems to me that hardly matters unless you plan to run the final
device off battery power, or put one in every home. Admittedly the
100mA USB limit may be a factor if there are a decent number of
chips involved, but that's just one option for power.


Depends on how complicated the circuit is. BITD I used to do boards
full of the stuff, and the power consumption was a serious issue. I was
doing frequency synthesis for early civilian direct-broadcast satcom, so
it had a bunch of 74S and early 74F parts. They sucked, but nobody but
the military could afford all-ECL systems.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

elektroda.net NewsGroups Forum Index - Electronics Components - Power a test TTL circuit from USB?

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