need a 12v to 20v converter preferably with 555

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onoffman

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I am looking for DCDC converter for solar light use please suggest


12v to 20v

i have a few components and 555 and 100uH inductor

i made this https://www.google.co.in/url?sa=t&r...=qTPolaeKkqh6a9LdOKs8Qg&bvm=bv.80642063,d.c2E


but the current is low , the 470uf if i put it goes to 3V or so ,
so kept the circuit open

load is 2 sets of 5W 5630led bulb panels


each has 10leds 5inseries *parallel*5 in series


i want to run from a 12V cell but the panels need

5*3=15V minimum
and 600mA current
 
Last edited:

Hi...

The given circuit input source from battery. So battery can support require current.

In solar panel It is how much watt???.. Your output power consumption is 9W. So you solar atleast 12W.
 

amayilsamy said:
Hi...

The given circuit input source from battery. So battery can support require current.

In solar panel It is how much watt???.. Your output power consumption is 9W. So you solar atleast 12W.
Click to expand...


panels i have is 10watts .. charges the cell during day

night cell to led power goes via dcdc converter
 

Basically Your output power is 9 W and 10 W. So, We believe it work 90% efficiency only you can get require output.

But panel can't give exactly 10W , It is give around 8 to 9W..

Post your block diagram..
 

amayilsamy said:
Basically Your output power is 9 W and 10 W. So, We believe it work 90% efficiency only you can get require output.

But panel can't give exactly 10W , It is give around 8 to 9W..

Post your block diagram..
Click to expand...

no light will run in d night ONLY !!
just taking power from from battery

by panels i meant LED panels

why would i put a street light in day ?:thinker:
 

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I suggest one thing replace the battery by 6 V, design charger for 6V with LM317. After charging the battery use boost converter for 6 to 15 V.

Present case we can't charge the 12 V battery by 12 V from penal. So, we one more boost converter for charging purpose.
It is some what costlier then first one.
 


i think you have mis understood the requirement , and guess that you have less idea on solar panels

12v panels charge cell very nicely - that is NOT the issue
-forget about the charging part

need a consistent "boost converter that can deliver 600mA @18 v 0r 20V
 




This is a 50-Watts supply for laptop. You can resize for 10-Watts. Inductor is very important here. Core has diameter of about 27mm. It has 21 turns of three parallel wires of 0.75mm dia. The choke has an inductance of about 44 mH and a resistance of about 0.1 ohms.
Frequency is 40KHz.
 

thanks a llot , i will hunt for a toroid ia have irf540 and others !!
 

Because the desired output voltage is almost a multiple of the supply V, then this voltage doubler might be of interest.

A 555 IC can generate the pulse train which drives the half-bridge.

 

BradtheRad said:
Because the desired output voltage is almost a multiple of the supply V, then this voltage doubler might be of interest.

A 555 IC can generate the pulse train which drives the half-bridge.

Click to expand...
that is very nice one ... are u sure it can pump 600mA,good it i can avoid the inductor
i left my inductor in my work city , nw in a small town ?

does it require bd140 /139 or higher rated transistors
can i do with FR 107 diodes
LEDs are protected with CCS for 600mA so voltage can be 22V no issue
 


thinking of using 7808 as low voltage cut off
1)+----- 7808---- 555 IC

2) the +ve batt directly to coil one end
 

onoffman said:
that is very nice one ... are u sure it can pump 600mA
Click to expand...

Yes, as long as you turn on the transistors sufficiently. Notice you will draw a few amperes from the supply.

does it require bd140 /139 or higher rated transistors
Click to expand...

Medium power (TO-220 package) should be okay.

can i do with FR 107 diodes
Click to expand...

The diodes can be normal (slow) speed. Notice they carry 2A or more.

LEDs are protected with CCS for 600mA so voltage can be 22V no issue
Click to expand...

If necessary you can reduce output V by reducing C1.
 

can you comment on using 7808 as low voltage cuttoff
This IC needs 12v to give 8v to 555 IC .so as the battery will drain less than 12V
the light will go shut off !


i will keep +Ve to the coil direct and only IC555 +ve from the regulator

do you see any complicasy ?
I dont want to deploy a OPamp

also have just 13v zener with me , and 7808IC
 

schmitt trigger said:
The 7808 is a voltage regulator....Is that what you want? Or do you want a voltage comparator? Your question is not clear.
Click to expand...

technically 7808 needs 12v for the output 8v
so i thought if i power 555 with it ,it will cut after vcc <12v
but my tests show it does not cut supply till 10V :sad::sad:
 

onoffman said:
but my tests show it does not cut supply till 10V :sad::sad:
Click to expand...

Of course not! the 78xx series do not have an undervoltage cutout function. They require about 2 to 2.5 volts above the output voltage to regulate.
Below that, they loose regulation.

If you want to implement an undervoltage cutout function (without opamps), you can use a zener and a transistor. But it won't have hysteresis. You will require a second transistor to make a discrete schmitt trigger function.
 


Thank you ..i have installed the ckt and for tests now it is manual off on batt low ,

as i have a low batt indicator , i can hook transistor switch to the -ve leg and do a LV cut .

It is in native town i returned from there ...thanx 'schmitt trigg'er
 

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