On Sun, 18 Sep 2011 17:09:30 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
>willy.vinken@skynet.be wrote:
>> On Sun, 18 Sep 2011 12:23:35 -0400, Jamie
>> <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
>>
>>
>>>willy.vinken@skynet.be wrote:
>>>
>>>
>>>>Anyone has a DC-DC (12v -> about 20v at 4 to 8 A) converter schematic
>>>>that proved reliable?
>>>
>>>How critical does the output need to be? What kind of device is it going
>>>to drive?
>>>
>>> P.S.
>>> With 8 amps out, you'll be expecting at least 15 amps on the input
>>>side..
>>>
>>> Jamie
>>>
>>
>>
>> Output voltage not critical. Say something between 19 and 22 volts.
>> The output should feed UC3906-controlled SLA battery chargers.
>> Right now, it is done with a 12v DC -> 220v AC converter ... aso.
>> The purpose is to load sailplane batteries where no mains is
>> available.
>>
>> Willy
>Is this it ?
>
>http://n5bia.com/docs/slachg_doc.pdf
>
Not this one, but very similar.
Willy
Reply by Jamie●September 18, 20112011-09-18
Nico Coesel wrote:
> Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com>
> wrote:
>
>
>>On Sun, 18 Sep 2011 23:06:50 +0200, Fred Bartoli <" "> wrote:
>>
>>
>>>Jamie a �crit :
>>>
>>>>willy.vinken@skynet.be wrote:
>>>>
>>>>>On Sun, 18 Sep 2011 12:23:35 -0400, Jamie
>>>>><jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
>>>>>
>>>>>
>>>>>
>>>>>>willy.vinken@skynet.be wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>>Anyone has a DC-DC (12v -> about 20v at 4 to 8 A) converter schematic
>>>>>>>that proved reliable?
>>>>>>
>>>>>>How critical does the output need to be? What kind of device is it
>>>>>>going to drive?
>>>>>>
>>>>>>P.S.
>>>>>> With 8 amps out, you'll be expecting at least 15 amps on the input
>>>>>>side..
>>>>>>
>>>>>>Jamie
>>>>>>
>>>>
>>>>
>>>>
>>>> +-------------+
>>>> | |
>>>> | |
>>>> | +----+-------+
>>>> | | |
>>>> | |/ |
>>>> +----|----+-| |
>>>> .-. | |> |
>>>> | | | | | 20VDC
>>>> | | | === | +-+-+--------+
>>>> '-' | GND +. ,+---+ A A |
>>>> + | +---- )|( +---++ | ---
>>>> | | |VDC )|( +---+(-+ ---
>>>> | | | +' '++--+ A A |
>>>> +----|-------------+ | | ++-+-+--------+
>>>> | | | | |
>>>> | +----+--|----+ |
>>>> | |/ | |
>>>> +-----|-----+| | |12VDC
>>>> .-. | |> | |
>>>> | | | | +----------------+
>>>> | | | |
>>>> '-' | ===
>>>> +-----+ GND
>>>>
>>>> CT Transformer, Caps coupled with the R's
>>>>
>>>>
>>>> The above is just an idea, you need to plug in the values, calculate
>>>>the current needed, in this case 16 amps, to know the values of the
>>>>R's that drive the power transistors..
>>>>
>>>> This a cheap mulitvibrator circuit that can generate a small amount of
>>>>boost which you can add in series with your existing system..
>>>>
>>>> A more advance circuit using MosFets and a driver circuit from a fixed
>>>>source would most likely work better but this will give you the idea.
>>>>
>>>> Excuse my bad drawing.
>>>>
>>>>Jamie
>>>>
>>>>
>>>
>>>The OP never stated it had to be isolated.
>>>
>>>A simple boost converter will do.
>>
>>Not to mention the ultimate saturation of the transformer in such a
>>simple-minded inverter.
>
>
> If you put a couple of diodes across the transistors or use MOSFETs
> with internal diodes AND allow for some dead time then there is enough
> room for the reset current to flow and prevent saturation.
>
Yes, I know it's a crappie circuit, but I did ask as to how critical it
had to be! :)
Actually, instead of using R's as the feed back, you use Caps and
then bias the transistors as in a AB class type amp, just some
minimum current to get it started. But, I did state, to couple the
R's with caps. The R is to be designated only to get a
small amount of current and the caps do the feed back. So, either way,
it'll work.
I suppose putting diodes on the (B) of each can help prevent the
transistors from over saturating, but they could also keep them not
saturating enough and heat up.
It's obvious there are better solutions but not with so few of parts
count :)
You should see the charge pump boost I made! I needed to keep
the voltage at 13 volts minimum for 2 radios I have that will not
operate below 12 volts. I was able to use a 555 timer with complemary
MosFets to charge pump a large capacitor with proper regulation and
safety crow bar in it, just in case ! That unit allows me to operate my
FT-100 even when transmitting, down to about 10 Volts at the plug. We
don't allow the charge pump to operate under that. we don't need to have
a dead battery.
Jamie
Reply by Nico Coesel●September 18, 20112011-09-18
Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com>
wrote:
>On Sun, 18 Sep 2011 23:06:50 +0200, Fred Bartoli <" "> wrote:
>
>>Jamie a �crit :
>>> willy.vinken@skynet.be wrote:
>>>> On Sun, 18 Sep 2011 12:23:35 -0400, Jamie
>>>> <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
>>>>
>>>>
>>>>> willy.vinken@skynet.be wrote:
>>>>>
>>>>>
>>>>>> Anyone has a DC-DC (12v -> about 20v at 4 to 8 A) converter schematic
>>>>>> that proved reliable?
>>>>>
>>>>> How critical does the output need to be? What kind of device is it
>>>>> going to drive?
>>>>>
>>>>> P.S.
>>>>> With 8 amps out, you'll be expecting at least 15 amps on the input
>>>>> side..
>>>>>
>>>>> Jamie
>>>>>
>>>
>>>
>>>
>>> +-------------+
>>> | |
>>> | |
>>> | +----+-------+
>>> | | |
>>> | |/ |
>>> +----|----+-| |
>>> .-. | |> |
>>> | | | | | 20VDC
>>> | | | === | +-+-+--------+
>>> '-' | GND +. ,+---+ A A |
>>> + | +---- )|( +---++ | ---
>>> | | |VDC )|( +---+(-+ ---
>>> | | | +' '++--+ A A |
>>> +----|-------------+ | | ++-+-+--------+
>>> | | | | |
>>> | +----+--|----+ |
>>> | |/ | |
>>> +-----|-----+| | |12VDC
>>> .-. | |> | |
>>> | | | | +----------------+
>>> | | | |
>>> '-' | ===
>>> +-----+ GND
>>>
>>> CT Transformer, Caps coupled with the R's
>>>
>>>
>>> The above is just an idea, you need to plug in the values, calculate
>>> the current needed, in this case 16 amps, to know the values of the
>>> R's that drive the power transistors..
>>>
>>> This a cheap mulitvibrator circuit that can generate a small amount of
>>> boost which you can add in series with your existing system..
>>>
>>> A more advance circuit using MosFets and a driver circuit from a fixed
>>> source would most likely work better but this will give you the idea.
>>>
>>> Excuse my bad drawing.
>>>
>>> Jamie
>>>
>>>
>>
>>The OP never stated it had to be isolated.
>>
>>A simple boost converter will do.
>
>Not to mention the ultimate saturation of the transformer in such a
>simple-minded inverter.
If you put a couple of diodes across the transistors or use MOSFETs
with internal diodes AND allow for some dead time then there is enough
room for the reset current to flow and prevent saturation.
--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------
Reply by Jim Thompson●September 18, 20112011-09-18
On Sun, 18 Sep 2011 23:06:50 +0200, Fred Bartoli <" "> wrote:
>Jamie a �crit :
>> willy.vinken@skynet.be wrote:
>>> On Sun, 18 Sep 2011 12:23:35 -0400, Jamie
>>> <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
>>>
>>>
>>>> willy.vinken@skynet.be wrote:
>>>>
>>>>
>>>>> Anyone has a DC-DC (12v -> about 20v at 4 to 8 A) converter schematic
>>>>> that proved reliable?
>>>>
>>>> How critical does the output need to be? What kind of device is it
>>>> going to drive?
>>>>
>>>> P.S.
>>>> With 8 amps out, you'll be expecting at least 15 amps on the input
>>>> side..
>>>>
>>>> Jamie
>>>>
>>>
>>>
>>> Output voltage not critical. Say something between 19 and 22 volts.
>>> The output should feed UC3906-controlled SLA battery chargers. Right
>>> now, it is done with a 12v DC -> 220v AC converter ... aso. The
>>> purpose is to load sailplane batteries where no mains is
>>> available.
>>>
>>> Willy
>> Is this it ?
>>
>> http://n5bia.com/docs/slachg_doc.pdf
>>
>>
>>
>>
>> +-------------+
>> | |
>> | |
>> | +----+-------+
>> | | |
>> | |/ |
>> +----|----+-| |
>> .-. | |> |
>> | | | | | 20VDC
>> | | | === | +-+-+--------+
>> '-' | GND +. ,+---+ A A |
>> + | +---- )|( +---++ | ---
>> | | |VDC )|( +---+(-+ ---
>> | | | +' '++--+ A A |
>> +----|-------------+ | | ++-+-+--------+
>> | | | | |
>> | +----+--|----+ |
>> | |/ | |
>> +-----|-----+| | |12VDC
>> .-. | |> | |
>> | | | | +----------------+
>> | | | |
>> '-' | ===
>> +-----+ GND
>>
>> CT Transformer, Caps coupled with the R's
>>
>>
>> The above is just an idea, you need to plug in the values, calculate
>> the current needed, in this case 16 amps, to know the values of the
>> R's that drive the power transistors..
>>
>> This a cheap mulitvibrator circuit that can generate a small amount of
>> boost which you can add in series with your existing system..
>>
>> P.S.
>> Keep in mind that while one side is building current, the other side
>> of this push pull will be generating double the voltage at the
>> collectors, so select transistors that can handle at least 30V on the
>> collector and ones that can handle 15 amps continuos with good heat sink.
>>
>> A more advance circuit using MosFets and a driver circuit from a fixed
>> source would most likely work better but this will give you the idea.
>>
>> Excuse my bad drawing.
>>
>> Jamie
>>
>>
>
>The OP never stated it had to be isolated.
>
>A simple boost converter will do.
Not to mention the ultimate saturation of the transformer in such a
simple-minded inverter.
...Jim Thompson
--
[On the Road, in New York]
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Reply by Jamie●September 18, 20112011-09-18
Fred Bartoli wrote:
> Jamie a �crit :
>
>> willy.vinken@skynet.be wrote:
>>
>>> On Sun, 18 Sep 2011 12:23:35 -0400, Jamie
>>> <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
>>>
>>>
>>>> willy.vinken@skynet.be wrote:
>>>>
>>>>
>>>>> Anyone has a DC-DC (12v -> about 20v at 4 to 8 A) converter schematic
>>>>> that proved reliable?
>>>>
>>>>
>>>> How critical does the output need to be? What kind of device is it
>>>> going to drive?
>>>>
>>>> P.S.
>>>> With 8 amps out, you'll be expecting at least 15 amps on the input
>>>> side..
>>>>
>>>> Jamie
>>>>
>>>
>>>
>>> Output voltage not critical. Say something between 19 and 22 volts.
>>> The output should feed UC3906-controlled SLA battery chargers. Right
>>> now, it is done with a 12v DC -> 220v AC converter ... aso. The
>>> purpose is to load sailplane batteries where no mains is
>>> available.
>>>
>>> Willy
>>
>> Is this it ?
>>
>> http://n5bia.com/docs/slachg_doc.pdf
>>
>>
>>
>>
>> +-------------+
>> | |
>> | |
>> | +----+-------+
>> | | |
>> | |/ |
>> +----|----+-| |
>> .-. | |> |
>> | | | | | 20VDC
>> | | | === | +-+-+--------+
>> '-' | GND +. ,+---+ A A |
>> + | +---- )|( +---++ | ---
>> | | |VDC )|( +---+(-+ ---
>> | | | +' '++--+ A A |
>> +----|-------------+ | | ++-+-+--------+
>> | | | | |
>> | +----+--|----+ |
>> | |/ | |
>> +-----|-----+| | |12VDC
>> .-. | |> | |
>> | | | | +----------------+
>> | | | |
>> '-' | ===
>> +-----+ GND
>>
>> CT Transformer, Caps coupled with the R's
>>
>>
>> The above is just an idea, you need to plug in the values, calculate
>> the current needed, in this case 16 amps, to know the values of the
>> R's that drive the power transistors..
>>
>> This a cheap mulitvibrator circuit that can generate a small amount of
>> boost which you can add in series with your existing system..
>>
>> P.S.
>> Keep in mind that while one side is building current, the other
>> side of this push pull will be generating double the voltage at the
>> collectors, so select transistors that can handle at least 30V on the
>> collector and ones that can handle 15 amps continuos with good heat sink.
>>
>> A more advance circuit using MosFets and a driver circuit from a fixed
>> source would most likely work better but this will give you the idea.
>>
>> Excuse my bad drawing.
>>
>> Jamie
>>
>>
>
> The OP never stated it had to be isolated.
>
> A simple boost converter will do.
>
>
That one is not isolated.
This scheme simply adds to the already available source, as noted
(boost). :)
Jamie
Reply by Fred Bartoli●September 18, 20112011-09-18
Jamie a �crit :
> willy.vinken@skynet.be wrote:
>> On Sun, 18 Sep 2011 12:23:35 -0400, Jamie
>> <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
>>
>>
>>> willy.vinken@skynet.be wrote:
>>>
>>>
>>>> Anyone has a DC-DC (12v -> about 20v at 4 to 8 A) converter schematic
>>>> that proved reliable?
>>>
>>> How critical does the output need to be? What kind of device is it
>>> going to drive?
>>>
>>> P.S.
>>> With 8 amps out, you'll be expecting at least 15 amps on the input
>>> side..
>>>
>>> Jamie
>>>
>>
>>
>> Output voltage not critical. Say something between 19 and 22 volts.
>> The output should feed UC3906-controlled SLA battery chargers. Right
>> now, it is done with a 12v DC -> 220v AC converter ... aso. The
>> purpose is to load sailplane batteries where no mains is
>> available.
>>
>> Willy
> Is this it ?
>
> http://n5bia.com/docs/slachg_doc.pdf
>
>
>
>
> +-------------+
> | |
> | |
> | +----+-------+
> | | |
> | |/ |
> +----|----+-| |
> .-. | |> |
> | | | | | 20VDC
> | | | === | +-+-+--------+
> '-' | GND +. ,+---+ A A |
> + | +---- )|( +---++ | ---
> | | |VDC )|( +---+(-+ ---
> | | | +' '++--+ A A |
> +----|-------------+ | | ++-+-+--------+
> | | | | |
> | +----+--|----+ |
> | |/ | |
> +-----|-----+| | |12VDC
> .-. | |> | |
> | | | | +----------------+
> | | | |
> '-' | ===
> +-----+ GND
>
> CT Transformer, Caps coupled with the R's
>
>
> The above is just an idea, you need to plug in the values, calculate
> the current needed, in this case 16 amps, to know the values of the
> R's that drive the power transistors..
>
> This a cheap mulitvibrator circuit that can generate a small amount of
> boost which you can add in series with your existing system..
>
> P.S.
> Keep in mind that while one side is building current, the other side
> of this push pull will be generating double the voltage at the
> collectors, so select transistors that can handle at least 30V on the
> collector and ones that can handle 15 amps continuos with good heat sink.
>
> A more advance circuit using MosFets and a driver circuit from a fixed
> source would most likely work better but this will give you the idea.
>
> Excuse my bad drawing.
>
> Jamie
>
>
The OP never stated it had to be isolated.
A simple boost converter will do.
--
Thanks,
Fred.
Reply by Jamie●September 18, 20112011-09-18
willy.vinken@skynet.be wrote:
> On Sun, 18 Sep 2011 12:23:35 -0400, Jamie
> <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
>
>
>>willy.vinken@skynet.be wrote:
>>
>>
>>>Anyone has a DC-DC (12v -> about 20v at 4 to 8 A) converter schematic
>>>that proved reliable?
>>
>>How critical does the output need to be? What kind of device is it going
>>to drive?
>>
>> P.S.
>> With 8 amps out, you'll be expecting at least 15 amps on the input
>>side..
>>
>> Jamie
>>
>
>
> Output voltage not critical. Say something between 19 and 22 volts.
> The output should feed UC3906-controlled SLA battery chargers.
> Right now, it is done with a 12v DC -> 220v AC converter ... aso.
> The purpose is to load sailplane batteries where no mains is
> available.
>
> Willy
Is this it ?
http://n5bia.com/docs/slachg_doc.pdf
+-------------+
| |
| |
| +----+-------+
| | |
| |/ |
+----|----+-| |
.-. | |> |
| | | | | 20VDC
| | | === | +-+-+--------+
'-' | GND +. ,+---+ A A |
+ | +---- )|( +---++ | ---
| | |VDC )|( +---+(-+ ---
| | | +' '++--+ A A |
+----|-------------+ | | ++-+-+--------+
| | | | |
| +----+--|----+ |
| |/ | |
+-----|-----+| | |12VDC
.-. | |> | |
| | | | +----------------+
| | | |
'-' | ===
+-----+ GND
CT Transformer, Caps coupled with the R's
The above is just an idea, you need to plug in the values, calculate
the current needed, in this case 16 amps, to know the values of the
R's that drive the power transistors..
This a cheap mulitvibrator circuit that can generate a small amount of
boost which you can add in series with your existing system..
P.S.
Keep in mind that while one side is building current, the other side
of this push pull will be generating double the voltage at the
collectors, so select transistors that can handle at least 30V on the
collector and ones that can handle 15 amps continuos with good heat sink.
A more advance circuit using MosFets and a driver circuit from a fixed
source would most likely work better but this will give you the idea.
Excuse my bad drawing.
Jamie
Reply by ●September 18, 20112011-09-18
On Sun, 18 Sep 2011 12:23:35 -0400, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:
>willy.vinken@skynet.be wrote:
>
>> Anyone has a DC-DC (12v -> about 20v at 4 to 8 A) converter schematic
>> that proved reliable?
>How critical does the output need to be? What kind of device is it going
>to drive?
>
> P.S.
> With 8 amps out, you'll be expecting at least 15 amps on the input
>side..
>
> Jamie
>
Output voltage not critical. Say something between 19 and 22 volts.
The output should feed UC3906-controlled SLA battery chargers.
Right now, it is done with a 12v DC -> 220v AC converter ... aso.
The purpose is to load sailplane batteries where no mains is
available.
Willy
Reply by Ian Field●September 18, 20112011-09-18
"Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:TKodq.15699$EP3.3110@newsfe05.iad...
> willy.vinken@skynet.be wrote:
>
>> Anyone has a DC-DC (12v -> about 20v at 4 to 8 A) converter schematic
>> that proved reliable?
> How critical does the output need to be? What kind of device is it going
> to drive?
>
> P.S.
> With 8 amps out, you'll be expecting at least 15 amps on the input
> side..
Might be best to direct the OP in the general direction of a blocking
oscillator style converter - with the stated load current I think forward
conversion mode is more likely to do the job than flyback, so some kind of
secondary winding is on the cards.
The 12V input isn't a vast headroom - a low VCEsat transistor would be well
worth having.
Reply by Jamie●September 18, 20112011-09-18
willy.vinken@skynet.be wrote:
> Anyone has a DC-DC (12v -> about 20v at 4 to 8 A) converter schematic
> that proved reliable?
How critical does the output need to be? What kind of device is it going
to drive?
P.S.
With 8 amps out, you'll be expecting at least 15 amps on the input
side..
Jamie