• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

How can I test this circuit???

Status
Not open for further replies.

thebigbasicq

New Member
http://www.uoguelph.ca/~antoon/gadgets/solar1g.htm (the circuit)

I have built this circuit with the following modifications:
1. I have used 200V zeners instead of the 400V(1N5117) zeners.
2. I have used a bead type 100uH inductor.

I am using a 6V 250mA solar panel. The MAX639 IC is a regulator IC. All resistors are 1/4 watt.

Now, how can I test this circuit. Whether it is working or not???

I don't want to connect Ni-Cd cells(infact i haven't bought them yet). I connected my multimeter accross the output terminals but it simply shows 0Volts? Meanwhile solar panel is supplying 6V to the circuit!

http://www.uoguelph.ca/~antoon/gadgets/solar1g.htm (the circuit)

Here is the datasheet of MAX639. It too contains the same circuit.
http://pdfserv.maxim-ic.com/arpdf/AppNotes/A0809.pdf

P.S.: it seems that the attachments are not working
 

Madmartin

New Member
Be Aware that you have a step-down regulatur. This means the cell voltage of your NiCd's has to be *less* than 6V (the voltage supplied from your panel). So you will only be able to charge 1-3 cells, I think. Without load, your Circuit won't do anything, i guess, which is typical for such regulators. Try adding a 1000 µF capacitor and a 470 ohms resistor in parallel to the output. Then measure again. Values are not critical, whatever you have left over... form 100 to 4700 µF and 100 to 1000 ohms.
Be informed that in the appnote from Maxim they used 12 solar cells which would accumulate to about 16-22 volt, I assume. However your setup should also work.
 

Roff

Well-Known Member
There is a typo in the original schematic, and Tony van Roon not only didn't catch it, he compounded it by adding one of his own. Those diodes are Schottkys, not 400 volt zeners (why in God's name would you need a 400v zener in a solar-powered battery charger ?). The closest number I could find was 1N5717, but I didn't find a datasheet. I suspect there are any number of Schottky rectifiers that will work. Pick one that can handle an amp continuous and will stand off 20 volts reverse, and it probably will work. The zener will probably also work, but not as a zener - it will function as an ordinary diode. Schottkys are more efficient - lower voltage drop and faster reverse recovery.

Tony said the diode was good for 7 amps continuous at 400 volts. This is 2.8kw! The actual rating is 7ma max, but this is reverse current
 

thebigbasicq

New Member
Thanx.

Here is what I did. I actually got tired of this circuit and what I did was extremely simple. I just connected the solar battery across the Ni-Cd cells and a shottky diode to prevent the backflow of current. And to my surprise this worked a 1,000,000 times better than the DAMN Max639 IC circuit. Though I want that circuit to function badly! But it just supplies me around 10mA of current when I have 250mA coming from my panels!

Any answers to why this is happening???
 

thebigbasicq

New Member
Thanx.

Here is what I did. I actually got tired of this circuit and what I did was extremely simple. I just connected the solar battery across the Ni-Cd cells and a shottky diode to prevent the backflow of current. And to my surprise this worked a 1,000,000 times better than the DAMN Max639 IC circuit. Though I want that circuit to function badly! But it just supplies me around 10mA of current when I have 250mA coming from my panels!

Any answers to why this is happening???
 

Roff

Well-Known Member
I can't tell you why it doesn't work, but I did discover by reading the datasheet that the diodes are supposed to be 1N5817, not 1N5117.
Heed what Madmartin said about the input voltage needing to be greater than the voltage of the batteries you're charging.
Read the original application note carefully and try to understand it.
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top