Issac,
     I haven't checked it but I would say that this board probably only=20
draws a half an amp. That is a guesstimate so don't quote me on it. I=20
might measure it when I go back out If all of the LEDs are on that would=20
be another 150mAs.
Thanks,
rich!

On 9/17/2015 7:26 AM, Isaac Marino Bavaresco wrote:
> Richard,
>
>
> You could use a Schottky diode. They usually have much lower Vf.
>
> I like the CDBA320 to CDBA380 series, up to 3 A of If and from 20V to 80
> V Vrrm, with a Vf of approx. 0.25 V. They are not very cheap though.
> The SD2114S040S8R0 supports currents up to 8 A and has a Vf of approx.
> 0.125V for small currents, a tough guy.
>
> But there are many other Schottky diodes, with various If, Vf and Vrrm
> ranges. Some of them are very affordable.
>
>
> By the way, my friends call me Isaac.
>
>
> Cheers,
>
> Isaac
>
>
>
>
>
> Em 17/09/2015 08:57, Richard R. Pope escreveu:
>> Marino,
>>       These are some really good points. I didn't put in a diode because
>> of the forward voltage drop. I'm using a 5 volt regulated supply and 4.5
>> volts would be right at the limit of what a 628A will tolerate. I'm
>> going to put these suggestions away for another day. I appreciate this.
>> Thanks,
>> rich!
>>
>> On 9/17/2015 6:34 AM, Isaac Marino Bavaresco wrote:
>>> Richard,
>>>
>>>
>>> It is a good idea to always provide some sort of reversal polarity
>>> protection to circuits. It is very common for equipment to be connected
>>> with the wrong polarity or a wrong power adapter.
>>>
>>> There are several approaches, suitable for various circuit requirements=
..
>>>
>>> 1) Just use a diode in series with the power input. Suitable when your
>>> circuit consumes a moderate current and you have a voltage regulator in
>>> the input or can tolerate a small voltage drop.
>>>
>>> 2) Use a fuse in series with the power input and a powerful diode
>>> connected cathode after the fuse and anode to ground. Your diode must b=
e
>>> strong enough to ensure the fuse will blow before the diode is damaged.
>>> The advantage is that you don't have the Vf loss from the diode when th=
e
>>> circuit is operating.
>>>
>>> 3) Use a power P-Channel MOSFET with its Drain pin connected to the
>>> power supply, Gate to ground and Source as output to the circuit. This
>>> circuit can be used for voltages up to approx. 20V, which usually is th=
e
>>> Gate-Source breakdown voltage. With the addition of a Zener diode and a
>>> resistor this limit can be raised.
>>> This circuit can be used for really high currents with very little
>>> energy loss. If you add another MOSFET in series in the opposite
>>> direction plus a TL431, another smaller MOSFET and some resistors, you
>>> have overvoltage protection also.
>>>
>>> 4) Use a relay with its coil with a diode in series connected to the
>>> power input. Use the normally-open contact to power your circuit. This
>>> method can be used for any current and voltage ranges and the only loss
>>> is the relay's coil current.
>>>
>>> Cheers,
>>>
>>> Isaac
>>>
>>>
>>> Em 17/09/2015 03:43, Richard R. Pope escreveu:
>>>> Bob and et al,
>>>>        Well I just make a goof! I was very fortunate. I hooked the pow=
er
>>>> to my control board up the wrong way. The PICs are tough little
>>>> monsters. Even though the power was hooked up the wrong way for almost
>>>> twenty minutes all of the PICs are fine. It looks like all that I
>>>> damaged were the tantalum capacitors. Wow! Good news. I'll be more
>>>> careful from now on. I appreciate all of the help that everyone has
>>>> given me.
>>>> Thanks,
>>>>
>
>

--=20
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