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How to modify 12-24v car phone charger?

Nauman Muhammad

May 9, 2016
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Sir Nauman Muhammad . . . . . . .




I need to break the circuit at pink marks?


Yes, use a single edge razor blade, Exacto hobby knife, surgical scalpel or SHARP pocket knife and cut two lines, side by side, in the copper foil, about the width of a metal paper clip and then peel the strip out. It will then leave a small gap in the copper foil.

I did not understand this point "Scrape the green resist from the foil to solder tin those areas initially.

You can not solder to a point that is covered with that green resist, until you scrape it off enough to reveal the bare copper foil that is beneath it.

We need the 0.1 ufd for High Frequency filtering and bypassing."


That is just an added part that we need to place in the circuit, it is the round orange capacitor, old equipment has MANY of these being used in their circuitry..



73's de Edd

Okay Sir!

I have done all except capacitor thing. I have an old circuit which has 102, 103, 501 and blank orange capacitors but does not have 104 numbered. Do we need exactly 104 number? Also please review the modified circuit.
image.jpeg
 

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CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
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This is just an FYI and is not implying that Ed's method of increasing an LM7806 output voltage to 9V by added Diodes in the 7806 GND leg is wrong. After all, many of us have been using this method successfully for decades! That's why I was very surprised to see that my Fairchild LM78xxx datasheet does not provide this method in the 'Typical Applications' section of the datasheet. After this many years of acceptance as common practice it's a mind blower!!!

Chris
 

73's de Edd

Aug 21, 2015
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Sir Nauman Muhammad . . . . . . .


Okay, it looks like the wiring is in place, and we just now need to do a little quality refinement to it.
Let's just start with the very top black wire, for a rework.
Cut another black wire just a little bit longer than the present one, strip both ends insulation
away, just a little bit more than you have presently stripped the existing one. ( ~ 1.25cm) Twist
the exposed fine wire ends very tightly, so that they will not come apart.
Use your soldering iron and apply solder at the very end and tin the wire up towards the insulation so that heat will be kept away from the insulation . . . . . until the very last of the solder tinning operation.
Repeat the procedure for the other wire end.
Take note of your existing left wires tinned area on the foil connection.
Scrape resist away upwardly, so that the existing solder blob can be extended up the board about that same amount again.

Hold the left part of the newly tinned wire up against that now extended solder blob and have the wires insulated end a the top, and clip the wire length such that the insulation to wire end will be the same length as that newly extended and freshly tinned solder blob.
Do a rapid application of one "drop" of solder to the center of that new tinned wire stub.
Hold the wire straight and in line with the side of the board and align the wire stub with the boards tinned solder blobs. Press in the iron, and the wire stub and foil blobs should melt and flow together.
This new . . . to you . . . "reflow soldering" technique will let you make controlled, positionable, neat and professional solder connections.
(Just FREEZE any movement for a ten count, so that any physical movement doesn't produce a bad solder joint. )
Take the remaining wire length and route it straight up the board and then make a bend to the right over to the point where you brought the wiring down to the now isolated pad of that final diode in the series string.
Use the same measuring of the length of that existing solder blob, to cut off the length of this next wire stub, so that the insulation is being just at the top and the wire is no longer than the length of the solder blob.
Use the same reflow solder method on making that connection.
Critique:
Your OLD wiring had TOO MUCH bared and frazzled copper wiring being exposed.

Rework that first black wire, and then we will be able to evaluate and then do the other 3 and use your NEW meter for double checking your foil dissections..

Also, that 103 cap that you found, will fill in for the 104.


Aside :
For the Peanut Gallery . . . . .

For any comments forthcoming on . . .why don't you just . . . .a zener diode . .ya da ya da ya.da.

As far as newcomers hope for any electronics part supply in Islamabad . . . .or Cairo in the past case of Pharoah . . . . . just refer to my previously supply URL in a just earlier post and check out your capacitor supply choices and then find only ten items.
Or check out the only one LM317 in stock.
MINIMUM order restrictions also apply.
I know that surplus electronics pulls, can yield some 1N4001 family of diodes for this Mcguyver type of work around.


73's de Edd


.




 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
4,960
Joined
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Messages
4,960
Personally I like solid wire for this kind of work. Small gauge too! Telephone or CAT5 or 6 even better. The stuff I really like has Teflon insulation that melts at a much higher temp than most common insulation found on small gauge wire. I also like a 'hot' iron that gets me on and off the joint FAST! Most novice solderers are on the joint waaaaay to long!

On that note Ed, I'm glad you critiqued the wiring because I didn't have to heart too. I don't think I'd have the patience to type out those detailed instructions either!! :)

BTW, I wouldn't bother with a Zener in there either. Not with 5 1N400x diodes already sitting on the board and available to do the job. ;) Best of all they help divide up the heat dissipated, which is a plus here because there's no heat sink on that 7806.

Chris
 

Nauman Muhammad

May 9, 2016
77
Joined
May 9, 2016
Messages
77
.



Sir Nauman Muhammad . . . . . . .


Okay, it looks like the wiring is in place, and we just now need to do a little quality refinement to it.
Let's just start with the very top black wire, for a rework.
Cut another black wire just a little bit longer than the present one, strip both ends insulation
away, just a little bit more than you have presently stripped the existing one. ( ~ 1.25cm) Twist
the exposed fine wire ends very tightly, so that they will not come apart.
Use your soldering iron and apply solder at the very end and tin the wire up towards the insulation so that heat will be kept away from the insulation . . . . . until the very last of the solder tinning operation.
Repeat the procedure for the other wire end.
Take note of your existing left wires tinned area on the foil connection.
Scrape resist away upwardly, so that the existing solder blob can be extended up the board about that same amount again.

Hold the left part of the newly tinned wire up against that now extended solder blob and have the wires insulated end a the top, and clip the wire length such that the insulation to wire end will be the same length as that newly extended and freshly tinned solder blob.
Do a rapid application of one "drop" of solder to the center of that new tinned wire stub.
Hold the wire straight and in line with the side of the board and align the wire stub with the boards tinned solder blobs. Press in the iron, and the wire stub and foil blobs should melt and flow together.
This new . . . to you . . . "reflow soldering" technique will let you make controlled, positionable, neat and professional solder connections.
(Just FREEZE any movement for a ten count, so that any physical movement doesn't produce a bad solder joint. )
Take the remaining wire length and route it straight up the board and then make a bend to the right over to the point where you brought the wiring down to the now isolated pad of that final diode in the series string.
Use the same measuring of the length of that existing solder blob, to cut off the length of this next wire stub, so that the insulation is being just at the top and the wire is no longer than the length of the solder blob.
Use the same reflow solder method on making that connection.
Critique:
Your OLD wiring had TOO MUCH bared and frazzled copper wiring being exposed.

Rework that first black wire, and then we will be able to evaluate and then do the other 3 and use your NEW meter for double checking your foil dissections..

Also, that 103 cap that you found, will fill in for the 104.


Aside :
For the Peanut Gallery . . . . .

For any comments forthcoming on . . .why don't you just . . . .a zener diode . .ya da ya da ya.da.

As far as newcomers hope for any electronics part supply in Islamabad . . . .or Cairo in the past case of Pharoah . . . . . just refer to my previously supply URL in a just earlier post and check out your capacitor supply choices and then find only ten items.
Or check out the only one LM317 in stock.
MINIMUM order restrictions also apply.
I know that surplus electronics pulls, can yield some 1N4001 family of diodes for this Mcguyver type of work around.


73's de Edd


.




Sir,

Thanks for critically evaluating my soldering and guiding me. One I am back from office, I will resold all new connection wires using the technique you told and I will place 103 Capacitor on the location required.

Please tell me how can I check foil dissections using my NEW Meter? :)
 

Nauman Muhammad

May 9, 2016
77
Joined
May 9, 2016
Messages
77
Personally I like solid wire for this kind of work. Small gauge too! Telephone or CAT5 or 6 even better. The stuff I really like has Teflon insulation that melts at a much higher temp than most common insulation found on small gauge wire. I also like a 'hot' iron that gets me on and off the joint FAST! Most novice solderers are on the joint waaaaay to long!

On that note Ed, I'm glad you critiqued the wiring because I didn't have to heart too. I don't think I'd have the patience to type out those detailed instructions either!! :)

BTW, I wouldn't bother with a Zener in there either. Not with 5 1N400x diodes already sitting on the board and available to do the job. ;) Best of all they help divide up the heat dissipated, which is a plus here because there's no heat sink on that 7806.

Chris

Yes, Ed guided me very perfectly from start and I hope I will end up in making a perfect converter. This 7806 has big heat sink ;) which I have removed for reworking.
 

Nauman Muhammad

May 9, 2016
77
Joined
May 9, 2016
Messages
77
.



Sir Nauman Muhammad . . . . . . .


Okay, it looks like the wiring is in place, and we just now need to do a little quality refinement to it.
Let's just start with the very top black wire, for a rework.
Cut another black wire just a little bit longer than the present one, strip both ends insulation
away, just a little bit more than you have presently stripped the existing one. ( ~ 1.25cm) Twist
the exposed fine wire ends very tightly, so that they will not come apart.
Use your soldering iron and apply solder at the very end and tin the wire up towards the insulation so that heat will be kept away from the insulation . . . . . until the very last of the solder tinning operation.
Repeat the procedure for the other wire end.
Take note of your existing left wires tinned area on the foil connection.
Scrape resist away upwardly, so that the existing solder blob can be extended up the board about that same amount again.

Hold the left part of the newly tinned wire up against that now extended solder blob and have the wires insulated end a the top, and clip the wire length such that the insulation to wire end will be the same length as that newly extended and freshly tinned solder blob.
Do a rapid application of one "drop" of solder to the center of that new tinned wire stub.
Hold the wire straight and in line with the side of the board and align the wire stub with the boards tinned solder blobs. Press in the iron, and the wire stub and foil blobs should melt and flow together.
This new . . . to you . . . "reflow soldering" technique will let you make controlled, positionable, neat and professional solder connections.
(Just FREEZE any movement for a ten count, so that any physical movement doesn't produce a bad solder joint. )
Take the remaining wire length and route it straight up the board and then make a bend to the right over to the point where you brought the wiring down to the now isolated pad of that final diode in the series string.
Use the same measuring of the length of that existing solder blob, to cut off the length of this next wire stub, so that the insulation is being just at the top and the wire is no longer than the length of the solder blob.
Use the same reflow solder method on making that connection.
Critique:
Your OLD wiring had TOO MUCH bared and frazzled copper wiring being exposed.

Rework that first black wire, and then we will be able to evaluate and then do the other 3 and use your NEW meter for double checking your foil dissections..

Also, that 103 cap that you found, will fill in for the 104.


Aside :
For the Peanut Gallery . . . . .

For any comments forthcoming on . . .why don't you just . . . .a zener diode . .ya da ya da ya.da.

As far as newcomers hope for any electronics part supply in Islamabad . . . .or Cairo in the past case of Pharoah . . . . . just refer to my previously supply URL in a just earlier post and check out your capacitor supply choices and then find only ten items.
Or check out the only one LM317 in stock.
MINIMUM order restrictions also apply.
I know that surplus electronics pulls, can yield some 1N4001 family of diodes for this Mcguyver type of work around.


73's de Edd


.




Sir,

I did resoldering work again, still not good but its working :/ Its giving me output voltage of 8.75-8.76. Now what's next?
image.jpeg
 

CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
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Joined
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Messages
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8.75V is pretty close but if you need a bit more voltage you do have one more diode left that you can add to the series string. This will bring the output voltage up to about 9.5V. I'm referring to the bottom diode (D1) in your last photo of the foil side of the board. It's currently connected to the 12V input.

On another note I don't think Ed is going to like the Orange wire connection to the Pos input pin of the regulator either. Way too much bare wire exposed looking for a place to short out on. I'm not thrilled with the solder job of the Green wire above it either.:D

On a second note I like to use Black wires for all ground connections because I immediately identify it as such. Red is SOP for positive rails too. ;)

Chris
 

Nauman Muhammad

May 9, 2016
77
Joined
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Messages
77
8.75V is pretty close but if you need a bit more voltage you do have one more diode left that you can add to the series string. This will bring the output voltage up to about 9.5V. I'm referring to the bottom diode (D1) in your last photo of the foil side of the board. It's currently connected to the 12V input.

On another note I don't think Ed is going to like the Orange wire connection to the Pos input pin of the regulator either. Way too much bare wire exposed looking for a place to short out on. I'm not thrilled with the solder job of the Green wire above it either.:D

On a second note I like to use Black wires for all ground connections because I immediately identify it as such. Red is SOP for positive rails too. ;)

Chris

Can I use 1N4007 diode (I have one extra from old torch light) instead of using 1N4001 at D1? And will 9.5v be safe for use with device requiring 9v?

Yeah I knew orange one is much weird and I will shorter it ends :p

The only reason I used these colorful wires is that I was running short of black and red wire so I tore apart my old LAN wire ;)
 

73's de Edd

Aug 21, 2015
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O.K. . . .then, to get that units output voltage up just above 9 Vdc, we need to add 1 more series diode in the string.
Find the third diode up from the RED wire DC power input of the board. That is being the third solder joint up on the right half of the board. Heat that solder joint and lift up the NON silver banded end of the diode from the board to a vertical position, as we need some working room.
Get ( your 1N4007 diode ) and then insert its non silver banded end into the hole that we just opened up and solder into place, just as the other one was done.
That now leaves the Silver banded lead of the new diode and the NON banded lead of the original diode to have their leads straightened.
You then have the leads crossed and resting against each other, and you then apply a drop of solder to electrically join them. Clip off any protruding excess lead length.

The new diode pair should then resemble a " V "
Your unit should now have a regulated output , just a small amount above 9 VDC.
Next I see that you made a partial switch to some solid wire, but did not properly
pre tin it.
Also the board needs a cleaning of excess flux and scrape abrasions with a stiff
brush and some 80 % Isopropyl alcohol.
In further evaluating the soldering joints being produced:
Is the wattage of your soldering written on it ?
It appears to not be hot enough, or its tip length needs to be shortened,
I will provide a picture of what I suspicion it to look like, on my next posting.

ADDENDA:
Yes the 4007 will be excellent, as it has a higher voltage rating than the 4001 !

73's de Edd

.
 
Last edited:

Nauman Muhammad

May 9, 2016
77
Joined
May 9, 2016
Messages
77
O.K. . . .then, to get that units output voltage up just above 9 Vdc, we need to add 1 more series diode in the string.
Find the third diode up from the RED wire DC power input of the board. That is being the third solder joint up on the right half of the board. Heat that solder joint and lift up the NON silver banded end of the diode from the board to a vertical position, as we need some working room.
Get ( your 1N4007 diode ) and then insert its non silver banded end into the hole that we just opened up and solder into place, just as the other one was done.
That now leaves the Silver banded lead of the new diode and the NON banded lead of the original diode to have their leads straightened.
You then have the leads crossed and resting against each other, and you then apply a drop of solder to electrically join them. Clip off any protruding excess lead length.

The new diode pair should then resemble a " V "
Your unit should now have a regulated output , just a small amount above 9 VDC.
Next I see that you made a partial switch to some solid wire, but did not properly
pre tin it.
Also the board needs a cleaning of excess flux and scrape abrasions with a stiff
brush and some 80 % Isopropyl alcohol.
In further evaluating the soldering joints being produced:
Is the wattage of your soldering written on it ?
It appears to not be hot enough, or its tip length needs to be shortened,
I will provide a picture of what I suspicion it to look like, on my next posting.

ADDENDA:
Yes the 4007 will be excellent, as it has a higher voltage rating than the 4001 !

73's de Edd

.

Alright that means we are close to target! Yeah I am so happy :) Alright I am going to add the diode.

After adding the diode converter is ready for use? And will it provide me 600mA rather than 500mA?

Yes I shifted to solid wire becuase previous one ended :/

Wattage is 45W.
 
Last edited:

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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That's a pretty crusty looking tip on your soldering iron. I suspect this photo was taken while the iron was cold (which doesn't help).

The first thing I would try is to heat it up, than using a newspaper sufficiently thick so as not to burn your fingers, draw the hot tip through the folded pages and see if you can get some of it off.

Your aim should be a nice shiny tip.
 

73's de Edd

Aug 21, 2015
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Sir Nauman Muhammad . . . . .

After adding the diode converter is ready for use?

Only, after you make your "wild" wiring solder connections correct.

In my looking at the 4 wires soldered to the circuit board
that were being made by the FACTORY worker,
I only approve of the quality of workmanship on the positive
output wire.. . . . .and I believe that your iron burned the insulation
on the negative wire.

And will it provide me 600mA rather than 500mA?

Yes it will, but it is IMPERATIVE that the 7806 has its heat sink firmly clamped to it.
AND ALSO a film of heat sink compound being between the mating tab of the 7806 and
the heat .sink.
That may be hard for you to find, unless you contact another hobbiest or electronics
service person in the know for the Islamabad supply situation .OR you might check out
plumbing suppliers as they use silicone grease on O rings associated with water faucets.
It is typically packaged and labeled like this:

shopping


Soldering:
If you can still loosen the two top set screws and pull out the soldering iron tip, examine it to see if there is a built up black oxide scale (which would be heat insulation) on the surface of the tip that is inside of the barrel of the irons heater. .
( it may also be inside the barrel of the iron itself. . . .MANY multiple side by side scrapes of a screwdriver cleans that out, )

If finding black oxide on the tip itself, file or wire brush down to unoxidized metal again.
Go to the blunt end and saw/grind off some length, so that the presently protruding tip will then be 2/3rds of its present length, doing that will get more intense heat out to your tips end.
You loose heat transfer in a HURRY on long tiplets.

Also, it looks like you have your irons tiplet properly and adequately tinned.
One thing that will help immensely is to have a just moist cellulose sponge nearby.
Just before you are going to make a solder connection, pull the tinned soldering tip across it and immediately add a bit of fresh solder to the tip and immediately move right over to the soldering connection to be made.
The fresh solder aids in maximum heat conduction into the work area and THEN you just add the required amount of solder . . .to the heated work . . . to complete your solder joint.



73's de Edd



.
 
Last edited:

Nauman Muhammad

May 9, 2016
77
Joined
May 9, 2016
Messages
77
That's a pretty crusty looking tip on your soldering iron. I suspect this photo was taken while the iron was cold (which doesn't help).

The first thing I would try is to heat it up, than using a newspaper sufficiently thick so as not to burn your fingers, draw the hot tip through the folded pages and see if you can get some of it off.

Your aim should be a nice shiny tip.

Okay I will try cleaning it using newspaper and will share snap of tip while its hot. :)
 

Nauman Muhammad

May 9, 2016
77
Joined
May 9, 2016
Messages
77
.

Sir Nauman Muhammad . . . . .

After adding the diode converter is ready for use?

Only, after you make your "wild" wiring solder connections correct.

In my looking at the 4 wires soldered to the circuit board
that were being made by the FACTORY worker,
I only approve of the quality of workmanship on the positive
output wire.. . . . .and I believe that your iron burned the insulation
on the negative wire.

And will it provide me 600mA rather than 500mA?

Yes it will, but it is IMPERATIVE that the 7806 has its heat sink firmly clamped to it.
AND ALSO a film of heat sink compound being between the mating tab of the 7806 and
the heat .sink.
That may be hard for you to find, unless you contact another hobbiest or electronics
service person in the know for the Islamabad supply situation .OR you might check out
plumbing suppliers as they use silicone grease on O rings associated with water faucets.
It is typically packaged and labeled like this:

shopping


Soldering:
If you can still loosen the two top set screws and pull out the soldering iron tip, examine it to see if there is a built up black oxide scale (which would be heat insulation) on the surface of the tip that is inside of the barrel of the irons heater. .
( it may also be inside the barrel of the iron itself. . . .MANY multiple side by side scrapes of a screwdriver cleans that out, )

If finding black oxide on the tip itself, file or wire brush down to unoxidized metal again.
Go to the blunt end and saw/grind off some length, so that the presently protruding tip will then be 2/3rds of its present length, doing that will get more intense heat out to your tips end.
You loose heat transfer in a HURRY on long tiplets.

Also, it looks like you have your irons tiplet properly and adequately tinned.
One thing that will help immensely is to have a just moist cellulose sponge nearby.
Just before you are going to make a solder connection, pull the tinned soldering tip across it and immediately add a bit of fresh solder to the tip and immediately move right over to the soldering connection to be made.
The fresh solder aids in maximum heat conduction into the work area and THEN you just add the required amount of solder . . .to the heated work . . . to complete your solder joint.



73's de Edd



.

Sir..

I will again work on my soldering connections. And yes the insulation was burnt by me :/..

Luckily I have a heat sink compound that I bought form my laptop's heat sink B-) so I will use that.

Alright I will have a look on my soldering iron's tip.. And will do as instructed.

I also have a new tip of soldering iron but it seems useless as it never heats up properly for making a solder :/
 

Nauman Muhammad

May 9, 2016
77
Joined
May 9, 2016
Messages
77
This is my new tip! Which doesn't heats and basically this came with my soldering iron. The current tip I am using is from older one.
image.jpeg
 

73's de Edd

Aug 21, 2015
3,636
Joined
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Messages
3,636
I can see the " blued " area, from prior heat concentration.
This might be a plated tip . . .but EVENTUALLY, one has to file or scrape a tip to re use it.

Install the tip:

Scrape a little area clean, that is right up against where it comes out of the barrel of the heater tube.
Will it accept a tinning ?
If so scrape and gradually move further outwards on the tip, in its progressive tinning.
Eventually you will reach the tip at the end, OR you will find that the external length of the
tiplet is not receiving enough heat transfer outwards from the heating tube.

GOOD to hear that you already had the heat sink compound .

73's de Edd


.
 

Nauman Muhammad

May 9, 2016
77
Joined
May 9, 2016
Messages
77
I can see the " blued " area, from prior heat concentration.
This might be a plated tip . . .but EVENTUALLY, one has to file or scrape a tip to re use it.

Install the tip:

Scrape a little area clean, that is right up against where it comes out of the barrel of the heater tube.
Will it accept a tinning ?
If so scrape and gradually move further outwards on the tip, in its progressive tinning.
Eventually you will reach the tip at the end, OR you will find that the external length of the
tiplet is not receiving enough heat transfer outwards from the heating tube.

GOOD to hear that you already had the heat sink compound .

73's de Edd


.

Finally after adding diode I got 9.4v then I tried to resolder after cleaning the old tip but it got black and black again and the non of the area is now accepting tinning on the tip.

I managed to solder (still very badly and bad solders).

The converter is working properly with my router. I have attached its own heat sink with new compound.

Now I will work on the solder tip as advised. Can I use sand paper to scrape the tip? And you are talking about new tip?

image.jpeg image.jpeg
 
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