| T O P I C R E V I E W |
| kivdenn |
Posted - Jan 04 2011 : 01:43:04 AM
Hey all I want to generate the most power possible from my solar panel and I can only achieve this by using a maximum power point tracker. I googled for some circuits and I landed on this one http://www.freewebs.com/acselectronics/buildppt.html but it was drawn by pen and pepper so I could not understand the capacitor value of pin 12 either it is 100nf or uf or pf and I cant find a way of getting back to the author, but that cap sets the oscilation frequency to 12khz. Can any body help me find the value of that cap either by cosely looking at the fuzy or recalculating it. Alternatively if any one has a similar circuit please post it. Thanks
Dennis
Download Attachment:  ppt2.jpg
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| 11 L A T E S T R E P L I E S (Newest First) |
| three_metre_jim |
Posted - Dec 16 2015 : 7:28:50 PM
Found this thread by accident while looking for a simple (no microprocessor) MPPT type solar charger. It's interesting that the posted circuit implements pseudo MPPT by monitoring the input voltage - there is an IC produced by Texas Instruments that works in exactly the same way, but it looks like the circuit here pre-dates it by a fair while.
Texas Instruments BQ24650: http://www.ti.com/product/BQ24650
There is a full explanation of how MPPT is implemented by controlling the input voltage.
Original page courtesy of the Internet Archive: http://web.archive.org/web/20091124055655/http://www.freewebs.com/acselectronics/buildppt.html
(you'll have to copy and paste the entire address as the forum seems to interpret the link as two separate addresses)
I saw a post saying you could use the mc34063 instead of the 78s40, but unfortunately, this is not true. The circuit works in reverse compared to normal connection of the switching regulator and needs the non-inverting comparator input that the 34063 does not have (the circuit tries to hold the input voltage down (pulling the open circuit voltage of the panel(s) towards the maximum power voltage) rather than regulate the output voltage). It may be possible using an external comparator and reference, if you'd like to go that way.
Hope this information is of help to someone.
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| shriram |
Posted - Aug 26 2014 : 11:43:43 PM
hi
lm78s40 equivalent is mc34063 the only thing is there is no
opamp and diode rest is same |
| pebe |
Posted - Jan 11 2012 : 04:21:56 AM
quote:
Originally posted by shruti
hi..we are working on the same circuit.I am not clear about the capacitor connected to pin 8 and 12 as their voltage ratings are not mentioned.Also value at pin 8 is not clear..please help as soon as possible
Read the data sheet!
All the information you need is there - including circuits and calculations on pages 5&6. |
| shruti |
Posted - Jan 11 2012 : 03:04:23 AM
hi..we are working on the same circuit.I am not clear about the capacitor connected to pin 8 and 12 as their voltage ratings are not mentioned.Also value at pin 8 is not clear..please help as soon as possible |
| kivdenn |
Posted - Feb 25 2011 : 06:46:26 AM
quote:
Originally posted by pebe
Here is the data sheet. That will show you how it works and how to calculate the cap at pin12.
http://www.datasheetcatalog.org/datasheets/134/502453_DS.pdf
I have failed to get the LM78s40, is there any substitute?
Thyanks |
| kivdenn |
Posted - Jan 27 2011 : 03:11:10 AM
Thanks its 100pf. I have buit the circuit and it works very well.It even increases my solar panel current by 1 amp. Thanks |
| pebe |
Posted - Jan 21 2011 : 04:15:41 AM
Here is the data sheet. That will show you how it works and how to calculate the cap at pin12.
http://www.datasheetcatalog.org/datasheets/134/502453_DS.pdf |
| kivdenn |
Posted - Jan 21 2011 : 02:24:58 AM
I need help on this people. Thanks |
| kivdenn |
Posted - Jan 14 2011 : 11:59:18 PM
Any contributions guys? |
| kivdenn |
Posted - Jan 07 2011 : 11:46:56 AM
quote:
Originally posted by ajmix2
Wow...that looks familiar. We were thinking of a tracker project like 3 years ago....it sorta died out. I stopped hearing from mrgone and then even I lost track of it.... the info is still online here somewhere.
Thanks sir for your impressive reply, a closer scrutiny at the fuzy image and the explanation,shows that the circuit seems to be able to perfom its duty of MPT but it should oscilate at 12khz determined by the capacitor at pin 12 but the author didnot write it clear, it apears as 100uf ceramic but thats too big. Is there a way we can recalculate the capacitor value of this cap?
Thanks |
| ajmix2 |
Posted - Jan 05 2011 : 04:27:08 AM
Wow...that looks familiar. We were thinking of a tracker project like 3 years ago....it sorta died out. I stopped hearing from mrgone and then even I lost track of it.... the info is still online here somewhere. |
