[TechAssist] Re: good sub 78m05a

  • From: "Philip Bader" <pbader@xxxxxxxxxxxxxxx>
  • To: <techassist@xxxxxxxxxxxxx>
  • Date: Fri, 30 Dec 2005 23:40:05 -0500

Dead God fellas, now don't try flipping a positive regulator trying to get 
negative out! I was kidding!
Phil
Philip Bader
Polk County School Board
Electronics Shop
Bartow,Fl.
(former owner, Jan Phyl TV INc.,
Winter Haven, Fl. from 1976-2006)
email: pbader@xxxxxxxxxxxxxxx

----- Original Message ----- 
From: "Christopher Barnak" <cbarnak@xxxxxxxxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Friday, December 30, 2005 2:09 PM
Subject: [TechAssist] Re: good sub 78m05a


> Phil,
> I use to design custom circuits when I used to work at the
> GE TV plant in Portsmouth, Va. We were never able to use
> a positive regulator for a negative regulator, we had to use
> the 79xx series regulators for negative voltages.
>
>
> Christopher Barnak, CET
> Norfolk Public Schools
> Electronics Maintenance
> 966 Bellmore Ave.
> Norfolk, Va. 23504
>
> Phone 757 628 3385
> Fax    757 628 3392
> cbarnak@xxxxxxxxxxxxx
>
>
>>>> pbader@xxxxxxxxxxxxxxx 12/30/05 11:16 AM >>>
> And that ground leg zener trick opens up a way to make a variable
> regulated
> DC power supply source.I imagine with a pot in the ground leg,or some
> such
> arrangement? Now, if you need a negative polarity output from a
> positive
> output reg IC,just turn the reg upside down.
> ;-)
> Phil
> Philip Bader
> Polk County School Board
> Electronics Shop
> Bartow,Fl.
> (former owner, Jan Phyl TV INc.,
> Winter Haven, Fl. from 1976-2006)
> email: pbader@xxxxxxxxxxxxxxx
>
> ----- Original Message ----- 
> From: "Gary McCartney" <gary@xxxxxxxxxxx>
> To: <techassist@xxxxxxxxxxxxx>
> Sent: Friday, December 30, 2005 11:11 AM
> Subject: [TechAssist] Re: good sub 78m05a
>
>
>> Yes, certainly a 78M05 can be subbed with a 7805. 78M05 is rated 0.5
>> amps and a 7805 is rated 1 Amp. There is no reason to even stock the
>> 78M05, just have a few 7805's on hand. Same goes for any other
> regulator
>> in the family- 7812, 7808, etc.
>>
>> Generally speaking, over the years reading these tech emails, I am
>> amazed at the lack of knowlege about these IC's, they are basic
>> fundamental electronic components like a diode or a transistor. Any
>> reasonings?
>>
>> Did you know that you can raise the output voltage of a 78xx series
>> regulator, by inserting a zener diode from the ground pin of the IC
> to
>> ground? If you want an 8V regulator but only have a 5V regulator 7805
> in
>> stock, you can insert a 3V zener from pin 2 of the reg to ground and
> get
>> an 8V reg. (as long as the back plane of the regulator IC is not
>> connected to ground itself because it is common with pin 2, unless
> of
>> course we are talking about a plastic backed IC)
>>
>>
>>
>>
>> Gary McCartney
>>
>> McCartney Electronics
>> Guelph Ontario Canada
>> Est. 1984
>> email: gary (at) number63.ca
>>
>>
>>
>>
>>
>>
>>
>> pete wrote:
>>> can i use a 7805a to sub a 78m05a anyone has done this before? its a
> 5
>>> volt regulator from a sony power supply model is kv35v35
>>> Perdomo Tv Inc Since 1972
>>> Miami.Fl
>>>
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