Knots are usefull in the day by day using of various things for camping, hiking, field days or who knows what and where.
I will put them here for my own reminder (also for anyone interested).
1. Lanyard for tools and portables:
2. Cowboy lasso
3. Line tensioners
4. Various 1
5. Various 2
I have an old Proxxon tool and, like many old power tools, the built-in speed controller is not working anymore.
So, I was thinking to do a separate box to set the speed because the actual method is not so suitable (altering the output voltage from my SMPS). You know, there are other "things" connected to it and modifing the voltage can harm them...
A DC current regulator was out of question because the Proxxon (like Dremel) need big currents when is loaded and the next thought was to make a variable PWM controller. So I searched into my boxes for a NE555 circuit and found a NE556 which is, basically, two 555 in the same IC.
I started to sketch the schematic and put it on a breadboard but there was too much soldering... HI HI :-)
Searching for a suitable case, I found one from an old project, already cut to accomodate a 2x16 LCD so I start to contemplate the possibility to make a speed controller which will show me the percentage and the input voltage and, why not, enable me to control other DC power tools.
I also found a small PCB already made for Arduino Pro-Mini and parallel controlled LCD so, i already had a good start!
Using PWM to controll DC motors is pretty convenient because the DC motor will "convert" variable width DC pulses into speed due to mechanical inertia. The most important thing is to find a semiconductor to work as much as possible to a switch!
Regular bipolar transistors are not suitable because they have a relative big resistance when the "switch" is closed so I decided to use a MOS-FET transistor.
I searched for one with a small Drain-Source resistance and found in my spare parts a IRF3205 which is advertised as a low resistance MOS-FET:
Of course, there are other suitable transistors but I wanted to have one that can handle some current without radiator...
Some words about the schematic
click on the picture for greater resolution
The working principle is simple; the speed potentiometer value is read by ADC (by reading the voltage of the wiper) and the value is converted from 1024 values into 255.
Then, this value is used to draw a nice bargraph, to print the % value and to generate the corresponding PWM value on pin 10 which will drive the MOS-FET transistor.
After testing it, I thought it was nice to have the input voltage on display so a voltage divider was made to be able to measure up to 30V with some accuracy.
My Arduino Pro-Mini was the 5V version so I choose a 7805 LDO to get those 5V for the board and the LCD. The board was powered by the RAW input, after the on-board voltage regulator.
Some words about the voltage divider and voltage measurement calibration
Arduino ADC's can measure 0-5V. Actually, the maximum value that can be measured with the ADC is precisely that of the Vcc applied to Arduino! So, in our case where the 5V are externally regulated from a 7805, we must measure the voltage at the RAW pin where 5V is applied. Usually the voltage is in the 4.9-5.1 V range and 5V is pretty accurate but if you want to have a greater precision, just replace "5" with the measured voltage in the code.
The voltage divider was made with what I had in my spare box, you can replace R4 and R5 with your values but keep in mind you must have a ratio able to keep the voltage at ADC port under 5V for the maximum voltage you want to use the device!
In the code, there is a "divider ratio" variable. This is how I get it:
Using this online voltage divider calculator, I used the following values, you can replace them with yours:
Input voltage: 12V
R1: 68 KOhm
R2: 5.1 KOhm
I got 0.837 V after the voltage divider.
The voltage ratio is therefore: 12/0.837 = 14.336917.
Of course, this is the theoretical result!
In practice, the ADC have it's own impedance, a stray resistor in DC so the real value of the voltage ratio is not so precise. Also, some errors will be present due to the real values of those resistors!
Some tweaking is needed to have a proper voltage indication so I set the voltage input into the device at 13V and on the LCD I got about "13.9V". I start to make some fine adjustments on that value (I did not calibrated the ADC reference too) and I ended with the
float divider_ratio = 13.1386;
which gave me pretty precise readings from 10 - 24V.
I think you got the ideea on what to do to your voltage divider to get it work right!
Here is the Arduino IDE code:
Somehow, you end up into an ICOM HF eco-system.
You have an IC-7300 or 7100 or 7000 or anything else; a radio that can do HF and you also have an IC-AH-4 the "wonder ATU" from ICOM.
You mod it to be more modular and portable as I did, ready for field use.
Maybe you want to use some other radios on the same antenna system or you want to go portable with a Xiegu G90 and you said to yourself: "I could put that AH-4 to good work but the ATU will not work with anything but ICOM radios".
Well, you may be wrong!
The AH-4 can and should be used with other radios because it is a small gem! But how?
A small independent control box can be used with other radios to tune various antennas, from wires to loop antennas and this is what I done recently.
It is in a crude form, maybe I will make it with the help of a microcontroller or maybe I will leave like it is now because, it is working well!
What do you need?
-ICOM AT connector;
-One Red and one Green LEDs
-Two PCF817 or similar optocouplers;
-Two 1N4148 or 1N4001 diodes (not mandatory);
-Three resistors between 1.2 KOhm and 2.2 KOhm (these values where tested);
-a temporary SPST push button;
-a small test PCB or any other solution to mechanically fix all together.
The schematic:
Power up the box. The Green LED will lit.
START and KEY have 5V (UP).
Set the radio to 5W in carrier mode (AM, FM, CW) and press PTT or CW Key.
Momentary press the button TUNE. The RED LED will lit.
The START line (from radio to ATU) will go down; the ATU will respond with KEY going down for the tuning cycle (request for carrier). Side note: if you didn't press the PTT or the CW Key before pressing TUNE, now it's the moment to do that!
During the tuning cycle, the AH-4 will request from the radio (which is not connected to the control lines) to transmitt a 5 W carrier.
Thus the IC-1 LED will lit and the corresponding transistor will keep START line down as long as the tuner need for the tuning cycle. Keep PTT or CW Key pressed on the transmitter.
When the RED LED is going off, the tuning solution is achieved.
Note: there are situations when the tuner will not find a solution for the antenna; the RED LED will go off and will lit again, the tuner will start a second sequence then will go in bypass mode.
I suggest using a small SWR meter between the radio and the ATU or watching the built in SWR meter to be sure a tuning solution was aquired.
This is my version:
From time to time, in discussion groups some fellow hams start worring about the voltage drop on the radio readout.
This is from a Xiegu G90 group:
> However, the 0.9 voltage difference was still there. I am fairly sure now the
> difference is due either to inaccuracy of G90 volt meter. (I do know it reads
> 0.2 volts low in receiver mode) or there is something internal to the G90
> causing the drop
I think some theory must be exposed to help users to understand what it is about the voltage readings in these radios (and others as well).
The voltage is measured with an ADC (Analog to Digital Converter) which "translates" variable voltages into digital variables.
One important thing to understand is "resolution" which is the lenght of the number that store the analog voltage value.
In our case, the ADC input of STM32F4xx can operate in 6-bit, 8-bit, 10-bit, and 12-bit configurable resolution.
Another important value is the maximum voltage that can be applied to the ADC input, which, in our case is 3V3.
Based on the datasheet of the uC, we can safely assume that the voltage is measured in 8-bit resolution (best resolution without some tricks that involve supplemental processor cycles which are precious because they are time-consumer in a uC which also have to do DSP things),
Resolution = ( Operating voltage of ADC ) / 2^(number of bits ADC).
Therefore, in our case:
Resolution = 3.3V/2^8 = 3.3/255 =12 mV.
This are the "steps" in which the voltage is measured in 8 bit resolution.
BUT! There is a big caveat here...
We cannot measure with this resolution the input voltage as is much over the 3.3V after which the input of the ADC will be destroyed!
So we put in line a voltage divider!
The divider will have to accept at least 20V (because the radio accepts input as much as 17V in normal operation.
Let's find out, what is the voltage divider ratio in our radio...
If we look on the schematic, Xiegu G90, the voltage divider is made with R63B and R67B 3.3KOhm and 470 Ohm respectively, which gave a ratio of 1:8 which means the resolution of the internal voltmeter is 0.096 (roughly 100mV) and the maximum voltage is 26.4 V!
So, any variation in the input voltage of more than 101 mV will be shown as a ... surprise, 200mV or 0.2V!
Simply said, the radio cannot show variations less than 0.2V!
As for the big variations when transmitting, again, from the schematic we can observe that the whole PARF components are tied to +13V.
The voltage tap used to measure the voltage is well beyond some components that will present a certain resistivity:
-power cord;
-fuse receptacle;
-RFI choke with both ground and positive leads;
-two MOSF-FETs used for reverse polarity protection and PowerON.
So, a 0.2-0.5 Ohm is a decent value for all of these and all of the above could explain the voltage swing measured by the internal DMM.
I think this will give a reason to enjoy the radio without worring about that voltage readout!
Cheers,
Adrian
Cateva module amplificatoare de radio frecventa integrate.
Functionale, recuperate din echipamente cu defectiuni in alte blocuri functionale.
Pretul este exclusiv transport.
1. MOTOROLA MHW7201A1 - UHF 400 MHz - 440 MHz - 150 Lei
Input/Output impedance: 50 Ohm
Minimum frequency: 400 MHz
Maximum Frequency: 440 MHz
Supply Voltage: 12.5V
Input power: 100mW
Output Power: 20W (max. 25W)
2. MITSUBISHI M67729H2 - 170 Lei
Input/Output impedance: 50 Ohm
Minimum frequency: 450 MHz
Maximum Frequency: 460 MHz
Supply Voltage: 12.5V (max.16V)
Input power: 100mW
Output Power: 25W (max. 30W)
3. MITSUBISHI M57710-A - 150 Lei
Input/Output impedance: 50 Ohm
Minimum frequency: 156 MHz
Maximum Frequency: 160 MHz
Supply Voltage: 12.5V (max 17V)
Input power: 200mW
Output Power: 30W (max. 35W)
4. MITSUBISHI M57796 MA - 120 Lei
Input/Output impedance: 50 Ohm
Minimum frequency: 144 MHz
Maximum Frequency: 148 MHz
Supply Voltage: 12.5V (max 16V)
Input power: 200mW
Output Power: 7W (5W @ 9V)
5. MITSUBISHI M68710H - 120 Lei
Input/Output impedance: 50 Ohm
Minimum frequency: 450 MHz
Maximum Frequency: 470 MHz
Supply Voltage: 9V (max 16V)
Input power: 30mW
Output Power: 2W
6. RA30H4047 Mitsubishi - 180 Lei
Input/Output impedance: 50 Ohm
Minimum frequency: 400 MHz
Maximum Frequency: 470 MHz
Supply Voltage: 12V (max 16V)
Input power: 50mW
Output Power: >30W
