Help With Ophir Head and Panel Meter-1 Battery

[rhd]

I could be wrong, but doesn't that IC still require a +Vin and a -V in order to produce a +/- output?

 

[lasersbee]

I could be wrong, but doesn't that IC still require a +Vin and a -V in order to produce a +/- output?

No it doesn't....
It only requires +5VDC and ground on the input to
produce +9VDC Ground and -9VDC on the output.


Jerry

 

[rhd]

No it doesn't....
It only requires +5VDC and ground on the input to
produce +9VDC Ground and -9VDC on the output.


Jerry

That's neat. I saw +Vin and -Vin as the pin descriptions on the datasheet, and assumed otherwise.

This could be a very simple IC for driving an ophir.

 

[lasersbee]

Those are common DC/DC converters that can be used
for that OPHIR Head Power circuit or any other circuit
that need a split rail supply. There are many others available
from other manufactures that will also work...

Jerry

 

[Nocturnal]

Awesome, Thanks Lasersbee and rhd. +1

how does this look:

 

[lasersbee]

Awesome, Thanks Lasersbee and rhd. +1

how does this look:

And put the Caps as close to the DC/DC converter as possible.
You may also want to put a 1uF tantalum 25V-35V cap on the
output of the 5V regulator to be sure it does not not go into
oscillation.


Jerry

 

[Nocturnal]

ok cheers for all the help :beer:

 

[rhd]

Hey Nocturnal -

I put together an eagle schematic of the circuit discussed here. It has a few slight differences. I altered it to send the 5V regulated feed to the LED display, as many of them require this.

If you want the schematic file (eagle), PM me and I'll send it to you. You can ignore the header on the right hand side, that's for an Arduino Nano.

 

[lasersbee]

A few things should be noted to correct the Drawing...

1) There should be a 1uF tantalum capacitor on the output
of the 5Volt Regulator to reduce the chance of the regulator
going into oscillation.

2) The OPHIR head connections should more correctly be
called OPH+9V and OPH-9V since the DC/DC converter
produces +/-9Volts.

Other than that it looks good to me...

Jerry

 

[Bionic-Badger]

Just a note: remember that tantalum capacitors are polarized. I fried an expensive $10 DC-DC converter because I put one in backwards, which shorted the power rails together when it destructed, destroying the far more expensive part. The fact that I didn't really even need the capacitor in the first place is the part that really irks me.

 

[rhd]

A few things should be noted to correct the Drawing...

1) There should be a 1uF tantalum capacitor on the output
of the 5Volt Regulator to reduce the chance of the regulator
going into oscillation.

2) The OPHIR head connections should more correctly be
called OPH+9V and OPH-9V since the DC/DC converter
produces +/-9Volts.

Other than that it looks good to me...

You're right. And I was also not crazy about my labeling of the "OPH(SIG)", but I'm not sure what else would be more fitting.

Bionic-Badger: Any reason you can think of not to simply use a ceramic non-polarized cap for the regulator?

 

[Bionic-Badger]

For this application the ceramic cap should work fine. Some linear regulators in there would also do a good job of cleaning up the power. Plus, using batteries means your power is already quite clean.

 

[rhd]

Alrighty - here we go

* C3 is a 1uF ceramic cap

 

[lasersbee]

Just a note: remember that tantalum capacitors are polarized. I fried an expensive $10 DC-DC converter because I put one in backwards, which shorted the power rails together when it destructed, destroying the far more expensive part. The fact that I didn't really even need the capacitor in the first place is the part that really irks me.

You're right. And I was also not crazy about my labeling of the "OPH(SIG)", but I'm not sure what else would be more fitting.

Bionic-Badger: Any reason you can think of not to simply use a ceramic non-polarized cap for the regulator?

You guys crack me up.... to replace a polarized part in case you
connect it in reverse is like saying we need a 555 with all the
pins the same and non identified so that we don't make a mistake
hooking up 8 pins...:crackup:

Just use a bit of care in connecting different types of electronic parts...

Yes... I've blown my share of incorrectly oriented parts but I've
learned to be more attentive because of it....

The Label of OPH(SIG) is correct because it is the data signal
connection...


Jerry

 

[rhd]

You guys crack me up.... to replace a polarized part in case you
connect it in reverse is like saying we need a 555 with all the
pins the same and non identified so that we don't make a mistake
hooking up 8 pins...:crackup:

Just use a bit of care in connecting different types of electronic parts...

Yes... I've blown my share of incorrectly oriented parts but I've
learned to be more attentive because of it....

LOL -

I was just asking because I have crap loads of 0603 and 0805 SMD ceramic caps from building drivers, but no tantalums

 

[lasersbee]

You can use either... I have learned to use a bypass/despiking Tantalum
capa of at least 1uF on the output of linear regulators and across any
supply line of all ICs. It has served me well over the years. You can use
nearly any kind of Caps of the correct values/voltages.

A Capacitor Voltage rule of thumb we use is.... Supply line Voltage X 2

If you look at the LaserBee IX or LaserBee II PCBs that run off a 9V
Battery... We have a 100uF Electrolytic on the input of the 5Volt LDO
Regulator and a 10uF cap on the output. Then we have a 1uF Tantalum
across the supply lines of the Op Amp and another one across the
supply lines of the MCU...
It seems like overkill on such a small PCB...
We have yet to see a LaserBee that exhibits Glitching or Noise problems...:beer:


Jerry