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Battery and Solar Stuff

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hi,
I cant get a fix on that relay number.???

Question, why do you want the light to stay ON allnight, rather than say, from dusk until bedtime..?:)


I dont need it to stay on all night, just thought it would be easier then puting in a timer to turn it off :)

As for my local, it is Melbourne - whats the consensus? go bigger and regulate the current?

if I turn it off after a few hours, maybe my location will be enough if I use only a fraction of the power each night?
 
I dont need it to stay on all night, just thought it would be easier then puting in a timer to turn it off :)

As for my local, it is Melbourne - whats the consensus? go bigger and regulate the current?

if I turn it off after a few hours, maybe my location will be enough if I use only a fraction of the power each night?


hi,
It shouldn't be too difficult to build a simple timer, triggered at dusk when the LED's come, for a set period of say, 6 hours.
If that cut the ON time in half, that will double the battery endurance and reduce the recharge time.

A HEF4060 ic could be used for the ON timing.

Whats the relay drive transistor type number.?
 
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the only transistor in the relay circuit is: C547A PH 70


hi,
Looking at the datasheet for the BC547A indicates only a 100mA collector current.

It should be possible to replace the BC547 with a ZTX 651 [or equiv] and use that to drive the LED's, remove the relay.
 

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Hi Eric,

European transistors don't drop the front part of the code off, it will be a 2SC547A - which is a 1A transistor - ne relation to a BC547.

Hi,

I did a Google, it came up with C547 as the BC547A family,, strange, I'll recheck of course.!

David,
Like this image.

EDIT:
Did a new search for 2SC547A, keep looping round to BC547A, must be having a bad hair day.!

Digikey list it, until searched for, then reports not found.?
 

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Wow, thanks Eric, thats awesome.

So that new Transistor to replace the relay will make it more efficient, but thats not for a timer is it?
 
Wow, thanks Eric, thats awesome.

So that new Transistor to replace the relay will make it more efficient, but thats not for a timer is it?

hi,
As Nigel points out, the existing transistor is rated at 1amp collector current, so it will do the job, dont need the ZTX.

For the timer I would suggest a HEF4060 with an RC osc [0.5sec/1sec], as a starting point.
 
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so same as your diagram that you did for me, just with the existing tranny ?

hi David,
I keep trying to get a datasheet for the 2SC547A, which if Nigel is correct, is a 1amp transistor.

All I keep getting a reference to is the BC547A, which is only 100mA.?

Perhaps someone out there has a 2SC547A datasheet....:confused:
 
hi David,
I keep trying to get a datasheet for the 2SC547A, which if Nigel is correct, is a 1amp transistor.

All I keep getting a reference to is the BC547A, which is only 100mA.?

Perhaps someone out there has a 2SC547A datasheet....:confused:

Check in "Towers International Transistor Selector", a book everyone should have :D
 
hi David,
I keep trying to get a datasheet for the 2SC547A, which if Nigel is correct, is a 1amp transistor.

All I keep getting a reference to is the BC547A, which is only 100mA.?

Perhaps someone out there has a 2SC547A datasheet....:confused:
www.datasheetarchive.com has Toshiba's very old datasheet that is written in Japanese.
The transistor is (was?) in an old metal case, probably TO-39.
**broken link removed**

The KEMO kit shows a transistor in a modern TO-92 plastic case so I think the kit uses a BC547A low current transistor that will be overloaded by all the LEDs it needs to drive.
 
audioguru;332309The KEMO kit shows a transistor in a modern TO-92 plastic case so I think the kit uses a BC547A low current transistor that will be overloaded by all the LEDs it needs to drive.[/QUOTE said:
Thanks 'agu'.

David it looks as though it will mean a transistor change.

Do you have any medium power npn transistors in the workshop.?
 
Well the Relay is Gone.. In fact the whole damn twilight kit is gone -

This is what I have now (see pic)

A Friend of mine has just told me there is a chance that 12v Will not run this circuit, can someone confirm or deny this please.... ?
 

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Well the Relay is Gone.. In fact the whole damn twilight kit is gone -

This is what I have now (see pic)

A Friend of mine has just told me there is a chance that 12v Will not run this circuit, can someone confirm or deny this please.... ?

hi David,
Where did this 'budget' circuit come from.?:)
The plastic C547 is not upto the job, especially as the circuit has no hysteresis.

Why does your friend think it wont work from 12V.?

Your image shows GREEN leds.?
 
scratch that, we just figured out that 12 volts is fine.

Now I just need to solve the problem of balancing charge during the day for what the circuit uses overnight

At the moment, the thought is either a timer to limit operating time or a freaking huge solar panel, so as not to worry or even care how much it uses :)

Any Ideas how I would add a timer to this? circuit ?
 
hi David,
Where did this 'budget' circuit come from.?:)
The plastic C547 is not upto the job, especially as the circuit has no hysteresis.

Why does your friend think it wont work from 12V.?

Your image shows GREEN leds.?

HI eric, Im using 10 1.2 AA batts for the power supply.

the transistor seems to work with just one set of LEDs plugged in, are you saying that as I add more, it will start to fail?

What is hysterisis?

(and yes, green superbirght leds (3.3v 20ma)
 
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HI eric, Im using 10 1.2 AA batts for the power supply.

the transistor seems to work with just one set of LEDs plugged in, are you saying that as I add more, it will start to fail?

What is hysterisis?

(and yes, green superbirght leds (3.3v 20ma)

hi David,
According to the data 'agu' and I have, the BC547 rated at only 100mA collector current.

So 6 chains of 20mA = 120mA.
The other point is, now you have removed the 'fast' switching action of the previous circuit, the led's could be 'half' ON, so the dissipation in the transistor could exceed its maximum rating.
 
Ok, so thats easy, I can just replace the Transistor (any thoughts as to which one I should use?)

as for the 'half on' issue, I have noticed this - depending on how dark it is will change the brightness of the LED's - thats OK with a bigger transistor though right?

Now Im still stuck with not getting enough juice out of the sun to fully recharge the batteries during one day - And if I do get a bigger solar panel, I have to solve the over charging issue :(
 
Ok, so thats easy, I can just replace the Transistor (any thoughts as to which one I should use?)
Any npn 500mA would be OK, I use the ZTX451 or 651 1amp series.

as for the 'half on' issue, I have noticed this - depending on how dark it is will change the brightness of the LED's - thats OK with a bigger transistor though right?
The transistor should be OK.

Now Im still stuck with not getting enough juice out of the sun to fully recharge the batteries during one day - And if I do get a bigger solar panel, I have to solve the over charging issue :(

hi,
For the over charging, look at a 'shunt' regulator.
 
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