12V 7.2AH SLA battery (8): UC2906 charger PCB constructed

 I have received the UC2906 board back from PCBWAY in China.  I've populated the board and am now ready to start testing.  I bought a strip of 1 inch wide by 1 inch thick aluminum from Lowe's and constructed a heat sink for the pass transistor, as can be seen in the photo.

click to enlarge

The circuit itself is a little bit of a challenge to test, since it requires using a SLA battery in various states of charge and discharge to test the various modes of the circuit.  I'm going to stop and design an active load to test the charger with.  I can also make the  active load so I can test other power supply circuit, such as all my Philmore 12V power supplies.  I'll start with a basic circuit as shown from Page 7.52 of the 2023 ARRL Handbook:

12V 7.2AH SLA battery (7): UC2906 charger PCB version 2

 I have revised the board layout from the previous post in this series (6) to use surface mount parts and use a 2 sided board. I also added a small prototype area consisting of a grid of 2.54mm spaced holes.   This will aid in bringing up the board.  I've ordered the board from PBCWAY.   See the diagrams below. 

I bought a bottle of ferric chloride etchant and I've been studying how to make two sided boards on Youtube videos.  I will try to make my own two sided PC Board.

click to enlarge

click to enlarge

12V 7.2AH SLA battery (6): UC2906 charger design

 Here is my third try at an SLA charger circuit.  It uses the UC2906/UC3906 smart charger IC as the charger controller.  The schematic of the test board is shown below.  The charger is going to be powered by an old discarded 19V laptop power supply.  Circuit description follows under the schematic.

click to enlarge

• The input power enters at J1 on the left. 
• Jumpers JP1 to JP3 and resistors R1 to R7 allow setting the current limit up to 1.75A in 0.125A increments. 
• LED1 to LED3 are used to display the state of the charger:  1) constant current state ,   2) overvoltage state, 3) float voltage state, or 4) trickle current state
• RA1, RB1, RC1, RD1, and RT3 are used to set the charge parameters according to the data sheet instructions:  overvoltage level, float voltage level, and trickle current.
• The power element is a TIP32C PNP transistor Q1
• The battery is connected at J2 on the right.

The diagram below is the layout for the test board: 

click to enlarge

The diagram below show a 3D rendering of the test board. 

click to enlarge

I am going to try etching a board using the toner method.  I've ordered some ferric chloride etchant and expect it to arrive on Friday.