Have I read this circuit schematic right?

[revans]

OK I need/want to make a 12v battery charger that itself is powered by 12v. I've attached the schematic that the website gave me.

Unfortunately, though I have soldered and worked with electronics before I'm not much at reading schematics. Trying myself to interpret it along with the help of the internet this is what I thought all the labels were:
F1 = 3A fuse
C1 = 33uF capacitor
C2 = Capacitor? It doesn't give value, maybe meant to be 5uF
C3 = 1000uF 25v capacitor
C4 = 1000uF 25v capacitor
C5 = 10uF 25v capacitor
R1 = 12 kohm resistor
R2 = 1 kohm resistor
R3 = 470 ohm resistor
R4 = 10 ohm 2 watt resistor
R5 = 10 ohm 2 watt resistor
U1 = 555 IC
U2 = 7815 voltage regulator
Q1 = 2SD525 transistor
Q2 = 2SB595 transistor
D1 = 1N4004 diode
D2 = 1N4004 diode
D3 = 1N4004 diode
D4 = 1N4004 diode
D5 = LED
J1 = No idea, what does the circle mean?
J2 = No idea, what does the circle mean?
J3 = No idea, what does the circle mean?
So, would anyone please be able to tell me if I've interpreted this right and what C2 and J1, J2, J3 mean? Thanks

Also, something I've never understood about circuit schematics:
Where is the other voltage input? This is for a charger which uses a 10-15v input to charge lead acid batteries, but the schematic only shows one point for 10-15v input. Where does the other wire go? The same conundrum also applies for the output leads which I'm meant to connect to the battery. This has always confused me and put me off building from schematics.

Also, I know the 3-pronged fork means "ground" but what are you actually meant to do with the ground wire? Just leave it hanging or solder to the enclosure or something?

Thanks for any help with my questions.

 

[ericgibbs]

OK I need/want to make a 12v battery charger that itself is powered by 12v. I've attached the schematic that the website gave me.

Unfortunately, though I have soldered and worked with electronics before I'm not much at reading schematics. Trying myself to interpret it along with the help of the internet this is what I thought all the labels were:
F1 = 3A fuse
C1 = 33uF capacitor
C2 = Capacitor? It doesn't give value, maybe meant to be 5uF
C3 = 1000uF 25v capacitor
C4 = 1000uF 25v capacitor
C5 = 10uF 25v capacitor
R1 = 12 kohm resistor
R2 = 1 kohm resistor
R3 = 470 ohm resistor
R4 = 10 ohm 2 watt resistor
R5 = 10 ohm 2 watt resistor
U1 = 555 IC
U2 = 7815 voltage regulator
Q1 = 2SD525 transistor
Q2 = 2SB595 transistor
D1 = 1N4004 diode
D2 = 1N4004 diode
D3 = 1N4004 diode
D4 = 1N4004 diode
D5 = LED

J1 thru J3 are connection points to the pcb.
They could be two pin connectors or just terminal pins

J1 = No idea, what does the circle mean?
J2 = No idea, what does the circle mean?
J3 = No idea, what does the circle mean?
So, would anyone please be able to tell me if I've interpreted this right and what C2 and J1, J2, J3 mean? Thanks

Also, something I've never understood about circuit schematics:
Where is the other voltage input? This is for a charger which uses a 10-15v input to charge lead acid batteries, but the schematic only shows one point for 10-15v input. Where does the other wire go? The same conundrum also applies for the output leads which I'm meant to connect to the battery. This has always confused me and put me off building from schematics.

The 3 prong gnd fork is the 'other wire'
In your circuit all the 'gnds' are really the 0V common line.

Also, I know the 3-pronged fork means "ground" but what are you actually meant to do with the ground wire? Just leave it hanging or solder to the enclosure or something?

There is no true ground on your circuit. The term ground is often used to mean 0V common

Thanks for any help with my questions.

hi,
Your cct acts as voltage multiplier, the two power transistors push pull drive that large capacitor, this increases the input voltage to approx *2.
This higher voltage is used to charge the battery.

Do you follow OK.?

 

[ericgibbs]

hi,

Edited your drawing.

Its 5nF nanoFarad

 

[revans]

Thanks Eric, I pretty much understand the ground thing now Except... I see you have labelled the positive terminal for voltage in - but I am unsure about where the negative input point would be.

Also, the "aux out" you have labelled "+Vout" is not actually the primary output. The designer of the circuit said "There is an auxiliary output, that provides about 20V at no load (depending on input voltage), and comes down as the load increases. I included this for charging 12V, 4Ah NiCd packs, which require just a limited current but not a limited voltage for charging." I will be using the charger to charge SLA batteries and would not be utilising J3 so I presume the +Vout for this would be J2. I have the same question about this though as above: I can see the positive output point but where would the negative output point be?

This is the webpage for the charger: ludens.cl/Electron/12Vcharger/12Vcharger.html

 

[ericgibbs]

Thanks Eric, I pretty much understand the ground thing now Except... I see you have labelled the positive terminal for voltage in - but I am unsure about where the negative input point would be.

Also, the "aux out" you have labelled "+Vout" is not actually the primary output. The designer of the circuit said "There is an auxiliary output, that provides about 20V at no load (depending on input voltage), and comes down as the load increases. I included this for charging 12V, 4Ah NiCd packs, which require just a limited current but not a limited voltage for charging." I will be using the charger to charge SLA batteries and would not be utilising J3 so I presume the +Vout for this would be J2. I have the same question about this though as above: I can see the positive output point but where would the negative output point be?

This is the webpage for the charger: ludens.cl/Electron/12Vcharger/12Vcharger.html

Hi,
The 14.3V charge voltage is a little high for a SLA, should be max of 13.8V/14V for fast charging.

I'll edit your dwg for the 0v and repost.

Is that any clearer.?

 

[revans]

Thanks so much Eric, you've been a great help. I reckon I'll be able to put it together fine now. Though, are you saying that I would not be able to charge an SLA with this circuit?

 

[ericgibbs]

Thanks so much Eric, you've been a great help. I reckon I'll be able to put it together fine now. Though, are you saying that I would not be able to charge an SLA with this circuit?

hi,
It should be OK to use with an SLA, I would remove the battery being charged when it reads 14Vdc.

The 7815 reg may need a heat sink.

When you have it working it would be interesting to know the efficiency of the charger. ie; Current in/ Current out

 

[revans]

Yeah you're right Eric, the circuit maker/designer guy says on his site that: "The resulting charge voltage is about 14.4V, which is fine for charging a gelled or AGM battery to full charge, but is too high as a trickle charger, so don't leave this charger permanently connected to a battery. If you would like to do just that, then add a second diode in series with D3!"
Do you think that adding the second diode in series with D3 would be a good idea; or would this permanently make it a trickle charger and make it useless for regular charging?

Also, he says one of it's downsides is low efficiency as the "charger wastes about as much power as it puts into the battery."

The maximum charge current is also 400ma and the LED lights up at 150ma.

I'm planning on using a 12v AC-DC adapter where you have put Battery 1.
Do you think that this one would be suitable: https://www.mini-box.com/24w-12v-2A-AC-DC-Power-Adapter

 

[ericgibbs]

hi,
I wouldnt add another diode, the adaptor looks OK at 2A.

From the designers notes it looks as though the input will be about 1A for 400mA charge.

You can buy 500mA/1A adaptors for 12V SLA's

 

[revans]

Yeah, thanks for the suggestion, but I also want to use the AC-DC adapter to power an Amp6-Basic (check out www.41hz.com) and it needs a bit more current than 500ma.

 

[ericgibbs]

Yeah, thanks for the suggestion, but I also want to use the AC-DC adapter to power an Amp6-Basic (check out www.41hz.com) and it needs a bit more current than 500ma.

hi,
You could add a shottky diode in series, that would give a charge voltage of 13.8V

https://uk.farnell.com/jsp/search/b...001&Ntt=schottky+diodes&Ntx=&_requestid=63968

 

[revans]

I assume you're talking about putting it in series with D3. What would be the advantage of having the voltage at 13.8v instead of 14.3v?

 

[ericgibbs]

I assume you're talking about putting it in series with D3. What would be the advantage of having the voltage at 13.8v instead of 14.3v?

It would give some degree of protection, in case you forgot to check the battery state.

 

[revans]

Oh great, come to think of it I probably should have figured that out myself. Anyway, could you please tell me if this would be suitable: **broken link removed** I searched for "schottky diode" and it came up with about 30 different ones so hopefully I picked a good one.

 

[ericgibbs]

Oh great, come to think of it I probably should have figured that out myself. Anyway, could you please tell me if this would be suitable: **broken link removed** I searched for "schottky diode" and it came up with about 30 different ones so hopefully I picked a good one.

hi,
It dosnt say what the forward voltage is and its not cheap.
We need a Vfwd of about 0.53V.

There is another option, look at this with a 7812 reg.

 

[revans]

Will the second option do the same thing as putting in a schottky diode? i.e. reduce the voltage to 13.8v?

And does the 500 ohm resistor need to be variable or did you just draw it like that?
(By saying 470R and 500R you mean 470 & 500 ohms, right?)

 

[mvs sarma]

Will the second option do the same thing as putting in a schottky diode? i.e. reduce the voltage to 13.8v?

And does the 500 ohm resistor need to be variable or did you just draw it like that?
(By saying 470R and 500R you mean 470 & 500 ohms, right?)

schottkky diode is better as it prevents battery from reaching the regulator. what is the current flow expected , better to use a 2amp version

 

[revans]

Ok thanks sarma, would you be able to give any more specific details on what sort of schottky diode? When I search for one on my local electronics shop's website (www.jaycar.co.nz) it gives about 30 different results and I don't know what is suitable apart from having a vfwd of 0.53, which didn't help much.

 

[mvs sarma]

Ok thanks sarma, would you be able to give any more specific details on what sort of schottky diode? When I search for one on my local electronics shop's website (www.jaycar.co.nz) it gives about 30 different results and I don't know what is suitable apart from having a vfwd of 0.53, which didn't help much.

Perhaps 1Amp diodes will suite as you need to charge at 400mA rate.The output of 7812 has to be raised to 13.8+0.53=14.33 or say 14.5 V. so the input needs to be around 18V.

Instead, if you did not freeze the circuit, you may well go for a single chip smps boost converter to get the needed 14.4 or 14.5 direct from any where 10.5 to 12V input. Being old timer, i used to prefer, MC34063A in boost mode
You may perhaps see the datasheet.