10KW Solar Charge Controller

Season Greeting Everyone,

Front Panel

Finally, the 10KW Solar Charge Controller was tested in a facility in Bangalore. Honestly, the facility in Bangalore did not have a proper 10KW system. So, we were restricted to only test upto 8KW.

Our Solar Charge Controller is designed with the mentioned specifications: -48V, 200A (yes, it is negative 48 Volts). The facility in Bangalore had a capacity to only run the system at 160A and was refusing to go beyond the ampere rate.

Few observations of the system during testing: the temperature rise was quite moderate for the power components used. The max. temperature recorded was about 60 degree Celsius. The temperature was recorders using Thermal Sensor with Fluke system which was connected to a PC through Serial Port.The Hyrda Software designed for Fluke Company was recording the temperature of all the power components in the Charge Controller for interval of 600 seconds.

Second key observation is the the wires that were used to the interconnect the whole Charge Controller. The theoretical knowledge generally around is that for 1 sq. mm of copper wire, we can use it for 10A rating. Well, that was quite false and proven by the test. We approximated the rating to 3A-4A per sq. mm of copper wire.

Well, we are already on the move to construct the next system with better enhanced heat-sinks to dissipate the heat faster and better, improved looks and far better design.

We are welcome to accept commercial requests as this Charge Controller is designed for Telecomm products and may not be suitable to all. Please feel free and send us requests or suggestions.

     

NorCal 20 - 99.90% Construction

Hello Everyone,

We have finished 99.90% construction of the NorCal 20. The remaining 0.10% is the testing of the NorCal 20 on air. The previous post had only the receiver unit assembled, now the transmitter unit is also constructed.

Soon, the test results will be posted. Stay tuned in......

Digital Ammeter using IC7107

Hello Everyone,

We have another great success to share with our readers and well wishers.

Digital Voltmeter using IC7107 was posted quite recently and we had made beautiful double sided PCB for the DVM's. Well we have managed to use the same PCB to display the Current too.

The formula is quite simple and it is not a new discovery as such. Refer to the diagram below:

We know that to measure voltage we connect the voltmeter in parallel and to measure current in a circuit we connect it in series. Now we all are aware of the famous Ohm's Law:

V = I * R

If we select the Shunt value or the R value to be 1, then the formula above reduces to:

V = I

So, keeping the points above in mind, I can effectively say that if R = 1 ohm or in orders of 1 milliohm, then when I measure the voltage it is as good as getting the current reading as V = I.

Hence the selection of the shunt value is quite crucial and the there is a a small change in the circuit. Refer the circuit below: Click Here

How did we test our Digital Ammeter?

We have selected a shunt of the specification 200A, 200 mV. So, that gets us R = 1 Milli-ohm.

Hence, by measuring the voltage across the shunt will be equivalent to calculating the current. That is, measuring 1 mV is like measuring 1A and 200mV is like measuring 200A.

Please note that the only difference in the PCB would to replace the 1Mohm used in the DVM by a 10K and the 1K resistance is removed.

In summary, we are just measuring the voltage and displaying it as current. Old school trick.

NorCal 20 - Under Construction

Hello Everyone,

We always had and will have a soft corner for HAM Radio Community and are willing to extend our helping hands to reach out.

A very Senior HAM operator and a well wisher approached us to help him build the famous NorCal 20 Transceiver kit.

What is NorCal 20?
It is a QRP CW Transceiver for 20 meters. (More details in depth coming soon!!)

In less than 2 weeks, our RnD Engineer has already finished the receiver part of the NorCal 20 and we are presently testing the receiver. Once we receive a few stations in the NorCal 20 Receiver, we shall progress to the Transmitter. Receiving a few stations on the receiver will give us confidence that the construction is fine to proceed to the transmitter.

Soon we shall have more updated of the famous NorCal transceiver.

Keep checking!!!!

Final Digital Voltmeter using IC7107

Hello Everyone,

It has been quite sometime since our last visit to the blog. Well the excuse would still be the same, we are busy with Secret X Project. Well the commercial project we are attacking at the moment requires the use of DVM to display voltages and also polarity.

PIC Microcontroller would be a good option but then to simply display voltage a microcontroller will be an overkill or under-utilized.

Hence, we choose a popular IC used in multimeters for a very long time. IC7107 is manufactured by Intersil and 3-1/2 Digit, LED Display, A/D Converter. It is purely dedicated to just drive 7-Segment LED Common Anode Display units and has built-in A/D Converter.

The beauty of the DVM is that it displays +/- voltages. The circuit is quite straight forward with the datasheet having the circuit and various modes of configuration. After building the DVM, the Reference Voltage has to be set to Calibrate the DVM to display the right voltage. This Calibration is achieved by setting the 10K pot. to either 100mV or 1V depending on the number of decimal places required. Also the DVM works on 5V only. The IC7660 is a voltage converter to generate -5V as negative reference in order to show us negative readings.

IC7107 Datasheet: Click Here
DVM Schematic: Click Here

Our previous post had the GPB (General Purpose Board) model. We got the PCB made to have the professional edge. Have a look at the pictures. Circuit is provided below.

Front and Back of the DVM (Quiz: which is the Front and Back ?)

DVM displaying Positive Voltage

DVM displaying Negative Voltage

 We would like to provide the schematic though the datasheet has provided which has a lot of ambiguity.