OT - Regulator recommendations (5V & 12V) and h ow do I create neg ative voltage
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Posts: 46,084
I'm sorry, I should have specified. The power source will be from a car's
cigarette adapter.
Original Message
From: Bob [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=oXWc7D-eKxBONYoli58eKJy8wWfKWMh-35vI6-dpTmaqjTlv6mpr_1BsxkMeA6H4s9gi]tesla@i...[/url
Sent: Tuesday, May 30, 2000 9:21 AM
To: basicstamps@egroups.com
Subject: Re: [noparse][[/noparse]basicstamps] OT - Regulator recommendations (5V & 12V) and
how do I create neg ative voltage
I am not sure what your initial voltage source will be rather
it be a wall transformer or you are building youe own power
supply or what but these are numbers for voltage regulators:
Positive voltage regulators:
78XX
Where XX = voltage regulated
So a 7805 would be a +5vdc regulator,
7812 = +12vdc regulator...etc
(BTW negative voltage regulators are nomenclatured the same way
but start with 79 instead of 78)
(But you need a negative voltage to begin with before regulating it)
Radio shaft carries the 7805 as part# 276-1770 (Rated 1 amp)
In a TO-220 case (The square 3 pin case)
and they have 2 heat sinks part# 276-1363, 276-1368
Jameco and other electronic mags sell the other voltage types
and packages like the TO-3 metal can type.
Jameco charges .29 each while Radio shaft charges $1.49
These components will regulate the voltage but will not filter
the voltage. Again I am not sure of your application.
As for the negative voltage, I ran into a need for this just last
week. I bought come 16x4 LCD's off eBay and after might near pulling
my hair out discovered that the reason I couldn't see anything on the
display was that I needed a negative voltage for the LCD contrast.
I bastardized a MAX232. A 16-pin chip whose purpose is to bring TTL
voltages to RS232 voltage levels. The MAX232 is powered by +5vdc and
along with 4 10uf capacitors, yields a negative voltage on one of the
pins. Its not a lot current, but it worked for me.
There is a chip, part# 7660CPA (Jameco part# 51174) which is easily
available. It is an 8-pin dip IC that is a CMOS +5vdc to -5vdc converter.
Costs $1.09. I need some of these.
Hope this helps,
Bob
At 07:51 AM 5/30/00 -0700, you wrote:
>What is a good 5V and 12V regulator? I know they are not terribly expensive
>so I guess anything under $10-15 or so would be fine.
>
>Also, I know this is probably a very simple question, but how do I create
>negative voltage?
>
>.·°·»
«·°·.
> -If everyone throws in their two cents worth, -
> -but its a penny for your thoughts...who keeps the profit?-
>
>
>
>
>
>
>
cigarette adapter.
Original Message
From: Bob [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=oXWc7D-eKxBONYoli58eKJy8wWfKWMh-35vI6-dpTmaqjTlv6mpr_1BsxkMeA6H4s9gi]tesla@i...[/url
Sent: Tuesday, May 30, 2000 9:21 AM
To: basicstamps@egroups.com
Subject: Re: [noparse][[/noparse]basicstamps] OT - Regulator recommendations (5V & 12V) and
how do I create neg ative voltage
I am not sure what your initial voltage source will be rather
it be a wall transformer or you are building youe own power
supply or what but these are numbers for voltage regulators:
Positive voltage regulators:
78XX
Where XX = voltage regulated
So a 7805 would be a +5vdc regulator,
7812 = +12vdc regulator...etc
(BTW negative voltage regulators are nomenclatured the same way
but start with 79 instead of 78)
(But you need a negative voltage to begin with before regulating it)
Radio shaft carries the 7805 as part# 276-1770 (Rated 1 amp)
In a TO-220 case (The square 3 pin case)
and they have 2 heat sinks part# 276-1363, 276-1368
Jameco and other electronic mags sell the other voltage types
and packages like the TO-3 metal can type.
Jameco charges .29 each while Radio shaft charges $1.49
These components will regulate the voltage but will not filter
the voltage. Again I am not sure of your application.
As for the negative voltage, I ran into a need for this just last
week. I bought come 16x4 LCD's off eBay and after might near pulling
my hair out discovered that the reason I couldn't see anything on the
display was that I needed a negative voltage for the LCD contrast.
I bastardized a MAX232. A 16-pin chip whose purpose is to bring TTL
voltages to RS232 voltage levels. The MAX232 is powered by +5vdc and
along with 4 10uf capacitors, yields a negative voltage on one of the
pins. Its not a lot current, but it worked for me.
There is a chip, part# 7660CPA (Jameco part# 51174) which is easily
available. It is an 8-pin dip IC that is a CMOS +5vdc to -5vdc converter.
Costs $1.09. I need some of these.
Hope this helps,
Bob
At 07:51 AM 5/30/00 -0700, you wrote:
>What is a good 5V and 12V regulator? I know they are not terribly expensive
>so I guess anything under $10-15 or so would be fine.
>
>Also, I know this is probably a very simple question, but how do I create
>negative voltage?
>
>.·°·»
«·°·.
> -If everyone throws in their two cents worth, -
> -but its a penny for your thoughts...who keeps the profit?-
>
>
>
>
>
>
>
Comments
Well now I have changed my mind totally! [noparse]:)[/noparse]
If you are using your car battery as a source, you
can use regulators but you better heatsink those
puppies good! It would be very inefficient.
Better to use one of those newer DC/DC converters.
They are switched and are much more effective.
These take a little more searching to find and
are more expensive. I found a couple in a Newark
catalog made by Newport. These are 1 watt
Newarks part numbers:
NMV1205S: Input +12vdc, Outputs +5 AND -5 vdc
NMV1212S: Input +12vdc, Outputs +12 AND -12 vdc
Both about $12.00 apiece
Do a search for DC/DC converters. They are out there.
Just watch out because some companies want like $100
each!
Bob
At 09:15 AM 5/30/00 -0700, you wrote:
>I'm sorry, I should have specified. The power source will be from a car's
>cigarette adapter.
>
>
Original Message
>From: Bob [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=C5c8SUVrf779yzq_iISIdjoK5DYC6_SKtaDo8fxgn1tXC9r8vGfrdI2JHh9zx-EbXuz5]tesla@i...[/url
>Sent: Tuesday, May 30, 2000 9:21 AM
>To: basicstamps@egroups.com
>Subject: Re: [noparse][[/noparse]basicstamps] OT - Regulator recommendations (5V & 12V) and
>how do I create neg ative voltage
>
>
>
>I am not sure what your initial voltage source will be rather
>it be a wall transformer or you are building youe own power
>supply or what but these are numbers for voltage regulators:
>
>Positive voltage regulators:
>
>78XX
>
>Where XX = voltage regulated
>
>So a 7805 would be a +5vdc regulator,
>7812 = +12vdc regulator...etc
>
>(BTW negative voltage regulators are nomenclatured the same way
>but start with 79 instead of 78)
>(But you need a negative voltage to begin with before regulating it)
>
>Radio shaft carries the 7805 as part# 276-1770 (Rated 1 amp)
>In a TO-220 case (The square 3 pin case)
>and they have 2 heat sinks part# 276-1363, 276-1368
>
>Jameco and other electronic mags sell the other voltage types
>and packages like the TO-3 metal can type.
>
>Jameco charges .29 each while Radio shaft charges $1.49
>
>These components will regulate the voltage but will not filter
>the voltage. Again I am not sure of your application.
>
>As for the negative voltage, I ran into a need for this just last
>week. I bought come 16x4 LCD's off eBay and after might near pulling
>my hair out discovered that the reason I couldn't see anything on the
>display was that I needed a negative voltage for the LCD contrast.
>
>I bastardized a MAX232. A 16-pin chip whose purpose is to bring TTL
>voltages to RS232 voltage levels. The MAX232 is powered by +5vdc and
>along with 4 10uf capacitors, yields a negative voltage on one of the
>pins. Its not a lot current, but it worked for me.
>
>There is a chip, part# 7660CPA (Jameco part# 51174) which is easily
>available. It is an 8-pin dip IC that is a CMOS +5vdc to -5vdc converter.
>Costs $1.09. I need some of these.
>
>Hope this helps,
>Bob
>
>
>
>At 07:51 AM 5/30/00 -0700, you wrote:
>>What is a good 5V and 12V regulator? I know they are not terribly expensive
>>so I guess anything under $10-15 or so would be fine.
>>
>>Also, I know this is probably a very simple question, but how do I create
>>negative voltage?
>>
>>.·°·»
«·°·.
>> -If everyone throws in their two cents worth, -
>> -but its a penny for your thoughts...who keeps the profit?-
>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>
>
>
>
input max and in a car you can get spikes and surges up over 100V. These
come from the load dumps when you have the Air Conditioner cycle or when
you press and release the brakes. Nasty environment for electronics.
Larry
At 12:47 PM 5/30/00 -0400, you wrote:
>Oh!
> Well now I have changed my mind totally! [noparse]:)[/noparse]
>If you are using your car battery as a source, you
>can use regulators but you better heatsink those
>puppies good! It would be very inefficient.
>Better to use one of those newer DC/DC converters.
>They are switched and are much more effective.
>These take a little more searching to find and
>are more expensive. I found a couple in a Newark
>catalog made by Newport. These are 1 watt
>
>Newarks part numbers:
>
>NMV1205S: Input +12vdc, Outputs +5 AND -5 vdc
>NMV1212S: Input +12vdc, Outputs +12 AND -12 vdc
>
>Both about $12.00 apiece
>
>
>Do a search for DC/DC converters. They are out there.
>Just watch out because some companies want like $100
>each!
>
>Bob
>
>
>
>
>
>
>
>At 09:15 AM 5/30/00 -0700, you wrote:
>>I'm sorry, I should have specified. The power source will be from a car's
>>cigarette adapter.
>>
>>
Original Message
>>From: Bob [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=CMExl2JV2frwjf70bEIYit45B6Fot5dFSX-lGXSlUfkNEIw2QUVMTeHVIcY2g4T80XHe3M2eEbA]tesla@i...[/url
>>Sent: Tuesday, May 30, 2000 9:21 AM
>>To: basicstamps@egroups.com
>>Subject: Re: [noparse][[/noparse]basicstamps] OT - Regulator recommendations (5V & 12V) and
>>how do I create neg ative voltage
>>
>>
>>
>>I am not sure what your initial voltage source will be rather
>>it be a wall transformer or you are building youe own power
>>supply or what but these are numbers for voltage regulators:
>>
>>Positive voltage regulators:
>>
>>78XX
>>
>>Where XX = voltage regulated
>>
>>So a 7805 would be a +5vdc regulator,
>>7812 = +12vdc regulator...etc
>>
>>(BTW negative voltage regulators are nomenclatured the same way
>>but start with 79 instead of 78)
>>(But you need a negative voltage to begin with before regulating it)
>>
>>Radio shaft carries the 7805 as part# 276-1770 (Rated 1 amp)
>>In a TO-220 case (The square 3 pin case)
>>and they have 2 heat sinks part# 276-1363, 276-1368
>>
>>Jameco and other electronic mags sell the other voltage types
>>and packages like the TO-3 metal can type.
>>
>>Jameco charges .29 each while Radio shaft charges $1.49
>>
>>These components will regulate the voltage but will not filter
>>the voltage. Again I am not sure of your application.
>>
>>As for the negative voltage, I ran into a need for this just last
>>week. I bought come 16x4 LCD's off eBay and after might near pulling
>>my hair out discovered that the reason I couldn't see anything on the
>>display was that I needed a negative voltage for the LCD contrast.
>>
>>I bastardized a MAX232. A 16-pin chip whose purpose is to bring TTL
>>voltages to RS232 voltage levels. The MAX232 is powered by +5vdc and
>>along with 4 10uf capacitors, yields a negative voltage on one of the
>>pins. Its not a lot current, but it worked for me.
>>
>>There is a chip, part# 7660CPA (Jameco part# 51174) which is easily
>>available. It is an 8-pin dip IC that is a CMOS +5vdc to -5vdc converter.
>>Costs $1.09. I need some of these.
>>
>>Hope this helps,
>>Bob
>>
>>
>>
>>At 07:51 AM 5/30/00 -0700, you wrote:
>>>What is a good 5V and 12V regulator? I know they are not terribly expensive
>>>so I guess anything under $10-15 or so would be fine.
>>>
>>>Also, I know this is probably a very simple question, but how do I create
>>>negative voltage?
>>>
>>>.·°·»
«·°·.
>>> -If everyone throws in their two cents worth, -
>>> -but its a penny for your thoughts...who keeps the profit?-
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>>
>>
>>
>
>
>
>
>
Larry G. Nelson Sr.
mailto:L.Nelson@i...
http://www.ultranet.com/~nr