Can someone recommend a part number / source for the optional voltage
regulator on the ooPIC-R?

thanks

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

I assume you want a second 5V regulator for powering external devices.
You need a LM7805. The package should be a TO-220. There are good up
to 1A or a certain wattage (depends on input voltage and sinking
capability, see datasheet). Mouser, Digikey, Jameco...All of them
carry them.

--- In o...@yahoogroups.com, "design.wonk" wrote:
>
> Can someone recommend a part number / source for the optional voltage
> regulator on the ooPIC-R?
>
> thanks
>

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

Your local Radio Shack should carry some if you dont feel like
waiting. Website shows it available at moste stores. Catalog #: 276-
1770. Same one I used. Works fine.

Patrick

------------------------------------



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--- In o...@yahoogroups.com, "Ask me, I wont Bite"
wrote:
>
Ummmm .... depending on which slot the auxiliary v-reg is to be
soldered into on the oopic-r board, a garden-variety LM7805 might be
the wrong pinout.

The proper part required might be the LM1084/1085/1086 part, which
has an LM317 pinout, different from the LM7805. Be careful what you
solder in.

> Your local Radio Shack should carry some if you dont feel like
> waiting. Website shows it available at moste stores. Catalog #: 276-
> 1770. Same one I used. Works fine.
>
> Patrick
>

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

The ooPIC-R only has one open spot for the optional voltage regulator.

--- In o...@yahoogroups.com, "dan michaels" wrote:
>
> --- In o...@yahoogroups.com, "Ask me, I wont Bite"
> wrote:
> >
> Ummmm .... depending on which slot the auxiliary v-reg is to be
> soldered into on the oopic-r board, a garden-variety LM7805 might be
> the wrong pinout.
>
> The proper part required might be the LM1084/1085/1086 part, which
> has an LM317 pinout, different from the LM7805. Be careful what you
> solder in.
>
> > Your local Radio Shack should carry some if you dont feel like
> > waiting. Website shows it available at moste stores. Catalog #: 276-
> > 1770. Same one I used. Works fine.
> >
> > Patrick
>
------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

When adding regulated servo power I assume that I would
1) Add a regulator
2) Move the PSL jumper form +SP to +SPR
3) Move jumpers s1 to s4 as needed
4) Connect a secondary 9V power source to pins 6 and 7 of the
optional power pins.

sound right?

--- In o...@yahoogroups.com, "tinslwc" wrote:
>
> I assume you want a second 5V regulator for powering external devices.
> You need a LM7805. The package should be a TO-220. There are good up
> to 1A or a certain wattage (depends on input voltage and sinking
> capability, see datasheet). Mouser, Digikey, Jameco...All of them
> carry them.
>
> --- In o...@yahoogroups.com, "design.wonk" wrote:
> >
> > Can someone recommend a part number / source for the optional voltage
> > regulator on the ooPIC-R?
> >
> > thanks
>
------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

--- In o...@yahoogroups.com, "design.wonk" wrote:
>
> When adding regulated servo power I assume that I would
> 1) Add a regulator
> 2) Move the PSL jumper form +SP to +SPR
> 3) Move jumpers s1 to s4 as needed
> 4) Connect a secondary 9V power source to pins 6 and 7 of the
> optional power pins.
>
> sound right?

Yes

As long as you don't want to use the existing voltage regulator that
is intended to driver peripheral and servo loads.

But, if you are talking about servo power only, why not plug a 6V
battery into +SP and Gnd and call it a day? You certainly don't need
sub 1% regulation for servos.

The power design of the R board is quite flexible. Well thought out...

I think Dan's point is to be absolutely certain that the pinout on the
R board for the 3d regulator actually matches a 7805 and not one of
the others. I don't have an R board so I can't check. But for servo
power I wouldn't be adding a regulator anyway.

Richard

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

--- In o...@yahoogroups.com, "rtstofer" wrote:
>
> --- In o...@yahoogroups.com, "design.wonk" wrote:
> >
> > When adding regulated servo power I assume that I would
> > 1) Add a regulator
> > 2) Move the PSL jumper form +SP to +SPR
> > 3) Move jumpers s1 to s4 as needed
> > 4) Connect a secondary 9V power source to pins 6 and 7 of the
> > optional power pins.
> >
> > sound right?
> >
> > Yes
>
> As long as you don't want to use the existing voltage regulator that
> is intended to driver peripheral and servo loads.
>
> But, if you are talking about servo power only, why not plug a 6V
> battery into +SP and Gnd and call it a day? You certainly don't need
> sub 1% regulation for servos.
>
> The power design of the R board is quite flexible. Well thought out...
>
> I think Dan's point is to be absolutely certain that the pinout on the
> R board for the 3d regulator actually matches a 7805 and not one of
> the others. I don't have an R board so I can't check. But for servo
> power I wouldn't be adding a regulator anyway.
>
> Richard
>

Richard,

Actually, I am not using it for servos. I want to run 6 Sharp IR
sensors on a single ooPIC-R (the big GP2Y0A700K0F sensors that draw
about 350mA each).

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

--- In o...@yahoogroups.com, "design.wonk" wrote:
> The ooPIC-R only has one open spot for the optional voltage
regulator.
>

In which case, you had better be sure you are soldering in the
correct part.
>
> --- In o...@yahoogroups.com, "dan michaels" wrote:
> >
> > --- In o...@yahoogroups.com, "Ask me, I wont Bite"
> > wrote:
> > >
> >
> >
> > Ummmm .... depending on which slot the auxiliary v-reg is to be
> > soldered into on the oopic-r board, a garden-variety LM7805 might
be
> > the wrong pinout.
> >
> > The proper part required might be the LM1084/1085/1086 part,
which
> > has an LM317 pinout, different from the LM7805. Be careful what
you
> > solder in.
> >
> >
> >
> > > Your local Radio Shack should carry some if you dont feel
like
> > > waiting. Website shows it available at moste stores. Catalog #:
276-
> > > 1770. Same one I used. Works fine.
> > >
> > > Patrick
> > >
>
------------------------------------



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--- In o...@yahoogroups.com, "design.wonk" wrote:
> --- In o...@yahoogroups.com, "rtstofer" wrote:
> >
> > --- In o...@yahoogroups.com, "design.wonk" wrote:
> > >
> > > When adding regulated servo power I assume that I would
> > > 1) Add a regulator
> > > 2) Move the PSL jumper form +SP to +SPR
> > > 3) Move jumpers s1 to s4 as needed
> > > 4) Connect a secondary 9V power source to pins 6 and 7 of the
> > > optional power pins.
> > >
> > > sound right?
> > >
> > >
> >
> > Yes
> >
> > As long as you don't want to use the existing voltage regulator
that
> > is intended to driver peripheral and servo loads.
> >
> > But, if you are talking about servo power only, why not plug a 6V
> > battery into +SP and Gnd and call it a day? You certainly don't
need
> > sub 1% regulation for servos.
> >
> > The power design of the R board is quite flexible. Well thought
out...
> >
> > I think Dan's point is to be absolutely certain that the pinout
on the
> > R board for the 3d regulator actually matches a 7805 and not one
of
> > the others. I don't have an R board so I can't check. But for
servo
> > power I wouldn't be adding a regulator anyway.
> >
> > Richard
> > Richard,
>
> Actually, I am not using it for servos. I want to run 6 Sharp IR
> sensors on a single ooPIC-R (the big GP2Y0A700K0F sensors that draw
> about 350mA each).
>
You are going to have a lot of trouble getting 2.1A out of a 7805 (1A
Max). You may need to look into building an off board regulator for
each one. I don't like to pull more than 0.5A from one regulator.
It also depends on your supply voltage as to how much current you can
get from a regulator. The higher your supply, the more power the
regulator has to dissipate. Pd = (Vs - 5) * Io. If I am going to be
pulling more than 50mA, I will usually put a heat sink on it.

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

--- In o...@yahoogroups.com, "tinslwc" wrote:
> --- In o...@yahoogroups.com, "design.wonk" wrote:
> >
> >
> > --- In o...@yahoogroups.com, "rtstofer" wrote:
> > >
> > > --- In o...@yahoogroups.com, "design.wonk" wrote:
> > > >
> > > > When adding regulated servo power I assume that I would
> > > > 1) Add a regulator
> > > > 2) Move the PSL jumper form +SP to +SPR
> > > > 3) Move jumpers s1 to s4 as needed
> > > > 4) Connect a secondary 9V power source to pins 6 and 7 of the
> > > > optional power pins.
> > > >
> > > > sound right?
> > > >
> > > >
> > >
> > > Yes
> > >
> > > As long as you don't want to use the existing voltage regulator
> that
> > > is intended to driver peripheral and servo loads.
> > >
> > > But, if you are talking about servo power only, why not plug a 6V
> > > battery into +SP and Gnd and call it a day? You certainly don't
> need
> > > sub 1% regulation for servos.
> > >
> > > The power design of the R board is quite flexible. Well thought
> out...
> > >
> > > I think Dan's point is to be absolutely certain that the pinout
> on the
> > > R board for the 3d regulator actually matches a 7805 and not one
> of
> > > the others. I don't have an R board so I can't check. But for
> servo
> > > power I wouldn't be adding a regulator anyway.
> > >
> > > Richard
> > >
> >
> > Richard,
> >
> > Actually, I am not using it for servos. I want to run 6 Sharp IR
> > sensors on a single ooPIC-R (the big GP2Y0A700K0F sensors that draw
> > about 350mA each).
> >
> You are going to have a lot of trouble getting 2.1A out of a 7805 (1A
> Max). You may need to look into building an off board regulator for
> each one. I don't like to pull more than 0.5A from one regulator.
> It also depends on your supply voltage as to how much current you can
> get from a regulator. The higher your supply, the more power the
> regulator has to dissipate. Pd = (Vs - 5) * Io. If I am going to be
> pulling more than 50mA, I will usually put a heat sink on it.
>

According to the way I read the datasheet (section 3-3 page 6 of 9)
the Average Supply Current (MAX) is just 50 mA and TYP is just 30 mA.

http://www.acroname.com/robotics/parts/R302-GP2Y0A700K0F.pdf

Richard

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

--- In o...@yahoogroups.com, "rtstofer" wrote:
>
> --- In o...@yahoogroups.com, "tinslwc" wrote:
> >
> >
> > --- In o...@yahoogroups.com, "design.wonk" wrote:
> > >
> > >
> > > --- In o...@yahoogroups.com, "rtstofer" wrote:
> > > >
> > > > --- In o...@yahoogroups.com, "design.wonk" wrote:
> > > > >
> > > > > When adding regulated servo power I assume that I would
> > > > > 1) Add a regulator
> > > > > 2) Move the PSL jumper form +SP to +SPR
> > > > > 3) Move jumpers s1 to s4 as needed
> > > > > 4) Connect a secondary 9V power source to pins 6 and 7 of the
> > > > > optional power pins.
> > > > >
> > > > > sound right?
> > > > >
> > > > >
> > > >
> > > > Yes
> > > >
> > > > As long as you don't want to use the existing voltage regulator
> > that
> > > > is intended to driver peripheral and servo loads.
> > > >
> > > > But, if you are talking about servo power only, why not plug a 6V
> > > > battery into +SP and Gnd and call it a day? You certainly don't
> > need
> > > > sub 1% regulation for servos.
> > > >
> > > > The power design of the R board is quite flexible. Well thought
> > out...
> > > >
> > > > I think Dan's point is to be absolutely certain that the pinout
> > on the
> > > > R board for the 3d regulator actually matches a 7805 and not one
> > of
> > > > the others. I don't have an R board so I can't check. But for
> > servo
> > > > power I wouldn't be adding a regulator anyway.
> > > >
> > > > Richard
> > > >
> > >
> > > Richard,
> > >
> > > Actually, I am not using it for servos. I want to run 6 Sharp IR
> > > sensors on a single ooPIC-R (the big GP2Y0A700K0F sensors that draw
> > > about 350mA each).
> > >
> > You are going to have a lot of trouble getting 2.1A out of a 7805 (1A
> > Max). You may need to look into building an off board regulator for
> > each one. I don't like to pull more than 0.5A from one regulator.
> > It also depends on your supply voltage as to how much current you can
> > get from a regulator. The higher your supply, the more power the
> > regulator has to dissipate. Pd = (Vs - 5) * Io. If I am going to be
> > pulling more than 50mA, I will usually put a heat sink on it.
> > According to the way I read the datasheet (section 3-3 page 6 of 9)
> the Average Supply Current (MAX) is just 50 mA and TYP is just 30 mA.
>
> http://www.acroname.com/robotics/parts/R302-GP2Y0A700K0F.pdf
>
> Richard
>

Richard,

I think that that might be referring to the logic circuit. The LED
requires more (see section 7-9). As you have seen from the data
sheet, this sensor has 5 wires. One pair supplies the logic circuit
and the other supplies the LED.

------------------------------------



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--- In o...@yahoogroups.com, "tinslwc" wrote:
> --- In o...@yahoogroups.com, "design.wonk" wrote:
> >
> >
> > --- In o...@yahoogroups.com, "rtstofer" wrote:
> > >
> > > --- In o...@yahoogroups.com, "design.wonk" wrote:
> > > >
> > > > When adding regulated servo power I assume that I would
> > > > 1) Add a regulator
> > > > 2) Move the PSL jumper form +SP to +SPR
> > > > 3) Move jumpers s1 to s4 as needed
> > > > 4) Connect a secondary 9V power source to pins 6 and 7 of the
> > > > optional power pins.
> > > >
> > > > sound right?
> > > >
> > > >
> > >
> > > Yes
> > >
> > > As long as you don't want to use the existing voltage regulator
> that
> > > is intended to driver peripheral and servo loads.
> > >
> > > But, if you are talking about servo power only, why not plug a 6V
> > > battery into +SP and Gnd and call it a day? You certainly don't
> need
> > > sub 1% regulation for servos.
> > >
> > > The power design of the R board is quite flexible. Well thought
> out...
> > >
> > > I think Dan's point is to be absolutely certain that the pinout
> on the
> > > R board for the 3d regulator actually matches a 7805 and not one
> of
> > > the others. I don't have an R board so I can't check. But for
> servo
> > > power I wouldn't be adding a regulator anyway.
> > >
> > > Richard
> > >
> >
> > Richard,
> >
> > Actually, I am not using it for servos. I want to run 6 Sharp IR
> > sensors on a single ooPIC-R (the big GP2Y0A700K0F sensors that draw
> > about 350mA each).
> >
> You are going to have a lot of trouble getting 2.1A out of a 7805 (1A
> Max). You may need to look into building an off board regulator for
> each one. I don't like to pull more than 0.5A from one regulator.
> It also depends on your supply voltage as to how much current you can
> get from a regulator. The higher your supply, the more power the
> regulator has to dissipate. Pd = (Vs - 5) * Io. If I am going to be
> pulling more than 50mA, I will usually put a heat sink on it.
>
Maybe I am way over my head on this one, but I was going to try to
split the sensors between the existing regulator and the additional
optional regulator. I had no problems running three of the sensors on
the ooPIC-R using just the existing regulator. But maybe I am reading
the datasheet wrong. When running the three sensors, the regulator
never even felt warm.

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

> Richard,
>
> I think that that might be referring to the logic circuit. The LED
> requires more (see section 7-9). As you have seen from the data
> sheet, this sensor has 5 wires. One pair supplies the logic circuit
> and the other supplies the LED.
>
Hmm... The way I understand these sensors is that they pulse the LED
and this does require several times the normal AVERAGE current. But,
in the long term, the AVERAGE current is in the 30-50 mA range.

So, most designers put a fairly large electrolytic capacitor (33 ufd
or more) immediately adjacent to the sensor to prevent the current
spikes from wandering around the PCB. It would also be good to put a
0.1 ufd ceramic at the same point. These want to be as close to the
sensor as possible.

Look at this schematic for the MiniSumo Mark III
http://www.junun.org/MarkIII/datasheets/Controller_SCH.pdf At grid B5
are the 33 ufd capacitors for the GP2D12's that are connected to J5 &
K6 (grid C6). On the PCB, these capacitors are mounted immediately
adjacent to the connectors.

HOWEVER, this is all a guess! I don't have any of these sensors so I
can't just take a simple measurement. But you can...

Section 7-9 has the word 'peak' for the LED current. This implies
that it is pulsed. What they are talking about is having a power
supply that doesn't go into overcurrent foldback when it sees the peak
current. But handling peak currents is the reason for bulk
capacitance like those electrolytics.

Richard

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

> Maybe I am way over my head on this one, but I was going to try to
> split the sensors between the existing regulator and the additional
> optional regulator. I had no problems running three of the sensors on
> the ooPIC-R using just the existing regulator. But maybe I am reading
> the datasheet wrong. When running the three sensors, the regulator
> never even felt warm.
>

I also don't have an R board. What regulator is being used? I
thought it was rated at 3A or so (heatsinked).

Richard

------------------------------------



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--- In o...@yahoogroups.com, "rtstofer" wrote:
>
> > Maybe I am way over my head on this one, but I was going to try to
> > split the sensors between the existing regulator and the additional
> > optional regulator. I had no problems running three of the sensors on
> > the ooPIC-R using just the existing regulator. But maybe I am reading
> > the datasheet wrong. When running the three sensors, the regulator
> > never even felt warm.
> > I also don't have an R board. What regulator is being used? I
> thought it was rated at 3A or so (heatsinked).
>
> Richard
>

Richard,
from the ooPIC homepage:

The OOPic-R's 3 voltage regulators are configured so that the logic
side of the board has a private one-Amp power supply, while the I/O
has a full five Amps of regulated power, plus an optional voltage
regulator that can be specified and installed as the end user needs.
A set of power selection jumpers allows different sections of the main
I/O lines to be connected to the various power supplies. In addition
to regulated power, a Servo Power input is provided so that a device
connected to the main I/O lines can be connected to unregulated power
when needed.
So it looks like I am OK without the additional regulator. I did not
realize that it had that capacity out of the box. Is there a way to
test how much power the sensor is using (I do have a Fluke 115 meter
available)?

thanks

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

At 06:29 PM 6/10/2008, design.wonk wrote:
>--- In o...@yahoogroups.com, "rtstofer" wrote:
> > I also don't have an R board. What regulator is being used? I
> > thought it was rated at 3A or so (heatsinked).
>
> from the ooPIC homepage:
>
>The OOPic-R's 3 voltage regulators are configured so that the logic
>side of the board has a private one-Amp power supply, while the I/O
>has a full five Amps of regulated power,

Those are MAXIMUM current draws under IDEAL conditions and those
conditions are NOT present on the OOPic-R. The tiny logic regulator
may be rated at one amp and the I/O regulator (LM1084) is rated at
five amps, but to supply those currents, they need minimal
differences between their input voltages and their regulated output
voltages and they would need proper heatsinks.

Neither of those regulators have heatsinks on the R board; the only
heat transfer path is through the metal back of the regulators to -
to what? A bit of copper on the circuit board? That part of the
LM1084 regulator is connected to its Vout (+5V), so it's not like
it's even connected to a big honking copper ground plane on the board.

If you ran the LM1084 off a 7.2V battery pack (for example) and tried
to pull 5 amps through it, there would be 11 watts of heat coming off
that regulator (this is basic Ohm's Law and is something every OOPic
user needs to be familiar with)

Where is all that heat going to go when there is no heatsink
present? I will let other elaborate further.
...Andy

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

> So it looks like I am OK without the additional regulator. I did not
> realize that it had that capacity out of the box. Is there a way to
> test how much power the sensor is using (I do have a Fluke 115 meter
> available)?
>
> thanks
>

I knew that second regulator was hefty but I had never bothered to
read that it was 5A. I don't have the R board and the S board has a
tiny regulator totally unsuited to driving peripherals.

>From what I read about your Fluke 115, it can measure DC amps with
autoranging. Page 12 of the user manual shows how to insert the leads
in series with the power to the sensor. Just put the Red lead to +5
and the black lead to the +5 input to the sensor. The sensor ground
connects to Gnd on the R board.

You might be able to measure MIN MAX and AVG as discussed on page 8 of
the user manual. It depends on whether the meter is fast enought to
capture the little spike. But, really, you don't care. Average is
what you want and you deal with the spikes with bulk capacitance.

User manual here: http://assets.fluke.com/manuals/114_____umeng0100.pdf

Richard

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

--- In o...@yahoogroups.com, "rtstofer" wrote:
>

>
> I knew that second regulator was hefty but I had never bothered to
> read that it was 5A. I don't have the R board and the S board has a
> tiny regulator totally unsuited to driving peripherals.
>
If I were using the oopic-r board, I would run "everything" added on
like sensors, etc, off the auxiliary 5A v.reg, and add no additional
loads whatsoever to the little smt v.reg that runs the cpu. I would
use a separate supply/battery for powering r/c servos [as opposed to
running them off the 5A v.reg].
------------------------------------



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--- In o...@yahoogroups.com, "dan michaels" wrote:
>
> --- In o...@yahoogroups.com, "rtstofer" wrote:
> > >
> > I knew that second regulator was hefty but I had never bothered to
> > read that it was 5A. I don't have the R board and the S board has a
> > tiny regulator totally unsuited to driving peripherals.
> >
> If I were using the oopic-r board, I would run "everything" added on
> like sensors, etc, off the auxiliary 5A v.reg, and add no additional
> loads whatsoever to the little smt v.reg that runs the cpu. I would
> use a separate supply/battery for powering r/c servos [as opposed to
> running them off the 5A v.reg].
>
OK, how does this sound:

I run all of my sensors off of the aux 5A v.reg and attach a small
heatsink (radioshack part # 276-1368) with thermal epoxy for good
measure. The main power is a a 9V 1A connected to the primary power
connector with a second 9V 1A source connected to one of the optional
power pins (7 or 8). This seems like a reasonable approach. I ran
three of the large sensors on the board with just a single 9V 1A
source with no apparent heat or performance problems. I have removed
the LEDs and switches on lines 5 and 6 and replaced them with header
pins to allow for 6 A2D lines. There are actually no servos involved
in this project. I am using the sensors and ooPIC-R for data acquisition.

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

> OK, how does this sound:
>
> I run all of my sensors off of the aux 5A v.reg and attach a small
> heatsink (radioshack part # 276-1368) with thermal epoxy for good
> measure. The main power is a a 9V 1A connected to the primary power
> connector with a second 9V 1A source connected to one of the optional
> power pins (7 or 8). This seems like a reasonable approach. I ran
> three of the large sensors on the board with just a single 9V 1A
> source with no apparent heat or performance problems. I have removed
> the LEDs and switches on lines 5 and 6 and replaced them with header
> pins to allow for 6 A2D lines. There are actually no servos involved
> in this project. I am using the sensors and ooPIC-R for data
acquisition.
>
I'm not sure how you would mount a heatsink but the PCB copper is
already doing this job. I think you are overanalyzing a problem that
doesn't exist. Even if you had 6 sensors at 50 mA each (AVG) you are
only talking about 300 mA - with a 5A regulator. You're worried about
a 5A regulator sourced with a 1A power supply.

Hook 'em up and see if the regulator gets hot. I'll bet it doesn't.

Richard

------------------------------------



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--- In o...@yahoogroups.com, "rtstofer" wrote:
>
> > OK, how does this sound:
> >
> > I run all of my sensors off of the aux 5A v.reg and attach a small
> > heatsink (radioshack part # 276-1368) with thermal epoxy for good
> > measure. The main power is a a 9V 1A connected to the primary power
> > connector with a second 9V 1A source connected to one of the optional
> > power pins (7 or 8). This seems like a reasonable approach. I ran
> > three of the large sensors on the board with just a single 9V 1A
> > source with no apparent heat or performance problems. I have removed
> > the LEDs and switches on lines 5 and 6 and replaced them with header
> > pins to allow for 6 A2D lines. There are actually no servos involved
> > in this project. I am using the sensors and ooPIC-R for data
> acquisition.
> >
> I'm not sure how you would mount a heatsink but the PCB copper is
> already doing this job. I think you are overanalyzing a problem that
> doesn't exist. Even if you had 6 sensors at 50 mA each (AVG) you are
> only talking about 300 mA - with a 5A regulator. You're worried about
> a 5A regulator sourced with a 1A power supply.
>
> Hook 'em up and see if the regulator gets hot. I'll bet it doesn't.
>
> Richard
>
You can mount a heatsink (permanently) to any chip with thermal
epoxy - but I think that you are right, I should just fire the thing
up and see if it works.
------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

>
> You can mount a heatsink (permanently) to any chip with thermal
> epoxy - but I think that you are right, I should just fire the thing
> up and see if it works.
>

I guess you could glue the heatsink to the plastic case but I'm not
sure how effective it would be. The VR is designed to move the heat
to the tab and fron the tab to the PCB. I would think the thermal
resistance of the plastic would be a limiting factor on the efficacy
of a glued on heatsink.

Richard

------------------------------------



(You need to be a member of oopic -- send a blank email to oopic-subscribe@yahoogroups.com )

--- In o...@yahoogroups.com, "rtstofer" wrote:
>
> > OK, how does this sound:
> >
> > I run all of my sensors off of the aux 5A v.reg and attach a
small radioshack part # 276-1368) with thermal epoxy for good
> > measure. The main power is a a 9V 1A connected to the primary
power connector with a second 9V 1A source connected to one of the
optional power pins (7 or 8). This seems like a reasonable
approach. I ran
> > three of the large sensors on the board with just a single 9V 1A
> > source with no apparent heat or performance problems. I have
removed the LEDs and switches on lines 5 and 6 and replaced them with
header pins to allow for 6 A2D lines. There are actually no servos
involved in this project. I am using the sensors and ooPIC-R for data
> acquisition.
> >
> I'm not sure how you would mount a heatsink but the PCB copper is
> already doing this job. I think you are overanalyzing a problem
that doesn't exist. Even if you had 6 sensors at 50 mA each (AVG)
you are only talking about 300 mA - with a 5A regulator. You're
worried about a 5A regulator sourced with a 1A power supply.
>
> Hook 'em up and see if the regulator gets hot. I'll bet it doesn't.
>
> Richard
>
Yeah, the first thing is to test it and see how hot it gets. If it
doesn't even feel hot, it's certainly ok. If it burns your finger,
then watch out. Even at full-load = 1A, the large v.reg is only
dissipating Pd = (9-5v)*1A = 4 watts. The pcb might be able to absorb
that much heat ok.

Also Richard, you should be able to epoxy a regular [.5"x.1"] TO220
heatsink to the "top" of a TO220 without too much interference with
other parts on the pcb - although I don't have an oopic-r to try it.

Also, the little smt v.reg will get hot very quickly under loading,
esp at 9v in. Those things are rated at something around 0.3W, and
that would be total load I = 0.3W / (9-5v) = 75-mA, not very much.

------------------------------------



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--- In o...@yahoogroups.com, "rtstofer" wrote:
>
> >
> > You can mount a heatsink (permanently) to any chip with thermal
> > epoxy - but I think that you are right, I should just fire the
thing up and see if it works.
> > I guess you could glue the heatsink to the plastic case but I'm not
> sure how effective it would be. The VR is designed to move the heat
> to the tab and fron the tab to the PCB. I would think the thermal
> resistance of the plastic would be a limiting factor on the efficacy
> of a glued on heatsink.
>
> Richard
>
This is true, but since the top of the chip can get pretty darn hot
too, adding a heatsink there should help.

------------------------------------



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--- In o...@yahoogroups.com, "dan michaels" wrote:
>
> --- In o...@yahoogroups.com, "rtstofer" wrote:
> >
> > >
> > > You can mount a heatsink (permanently) to any chip with thermal
> > > epoxy - but I think that you are right, I should just fire the
> thing up and see if it works.
> > >
> >
> > I guess you could glue the heatsink to the plastic case but I'm not
> > sure how effective it would be. The VR is designed to move the heat
> > to the tab and fron the tab to the PCB. I would think the thermal
> > resistance of the plastic would be a limiting factor on the efficacy
> > of a glued on heatsink.
> >
> > Richard
>

I have just confirmed (with the meter) that these sensors do draw
about 330mA. I will be gluing a heatsink onto the LM1084. The
housing seems to be ceramic rather than plastic, so it should help to
eliminate some heat.
>
> This is true, but since the top of the chip can get pretty darn hot
> too, adding a heatsink there should help.
>

------------------------------------



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