prikupets
Nov 02, 2005, 09:03 AM
Four high-current channels RC relay, which is handled by one transmitter channel.
Overview
The device is intended for turning on one of four channels by the command from transmitter. Channels can be activated in forward or backward sequence – each stick moving from neutral position to maximum turns on next channel and holds it while stick is not neutral. Moving stick to minimum position switches channels in backward order. Channels are looped – #1 goes after #4, and #4 after #1 in reverse.
I’m going to use this device to blow up the fireworks from my flying model or launch “rocket” from the boat. I make home-made detonators from small electric flashlights bulbs for 2.5-3.5V voltage. I cracks bulbs and I coat bulb’s helix with explosive matter from the matches heads, attenuated with few drops of water. The firework’s primer is coated also and connected with the helix till the matter is dried. So, when a channel is turned on, its bulb fires the matter and primer, and after couple of seconds the firework fires too. If you need to drop a “bomb”, you need to hang the firework on some thread, which is tied to the middle of the primer and fixed by drop of flammable glue (CA and liquid glass SiO2 do not match), like polyurethane glue.
Logic of work
Relay can connect one of the four loads to the motor battery. It plugs into one receiver channel and is operating by the following algorithm:
1) When the device initializes, no one channel is active. The device beeps shortly and starts to wait when the stick is neutral. When it got neutral position, it beeps twice more.
2) The device waits in loop, when stick is goes to almost maximum or minimum position;
3) If stick moves to maximum and stays in this position for some time (see constant in the source), the device turns channel #1 on and holds while stick is not in neutral again. The device beeps one time, which means that channel #1 was activated.
4) Moving stick to neutral turns off the channel #1. Next moving to the maximum will activate channel #2 and so on and loop after channel #4. Moving stick to the minimum direction turns channels on in the backward way.
Construction
Power FETs
IRF7311 FETs, used in the device, can pass thru more 10A in short pulse, and about 5-6A continues of current. Ground of the battery and servo cable must be common – and it is so when you use regular ESC with BEC.
Beeps and LED
Beeps are produced by beeper with generator. This kind of beeper eats about 40 mA – it is twice as big as PIC can give. So, if you need a sound acknowledgement of the device operation, you need buffer the PIC output with a FET. I used BS170 FET for this. The LED (if you need it) can be connected to the output pin directly or after buffer (if you have it). If you use 3V sound generator (i.e. HCM1203X) you should connect 50 Ohm resistor in series with it. There is no need in resistor if you use 6V beeper (HCM1206X).
Firmware
You can use PIC12F629 or PIC12C509 with corresponded firmware. PIC12F629 hex file MUST be corrected before burning in: the OSCCAL constant must be changed to your PIC instance value. You should read OSCCAL one byte value from the 3EEh address of PIC factory set memory, open hex file in any text editor, search for A0308316AC and change A0 to your OSCAL value. Save the file and burn it in.
There should be no any changes for PIC12C509 hex file, so it may be easier to use it. Please note, that PIC12C509 is one-time microcontroller, so you can program it only once.
Disclaimer
Use this device on your own risk.
Limitations
Please do not do anything commercial (sale or produce for sale) with it without contacting with me in this thread.
Overview
The device is intended for turning on one of four channels by the command from transmitter. Channels can be activated in forward or backward sequence – each stick moving from neutral position to maximum turns on next channel and holds it while stick is not neutral. Moving stick to minimum position switches channels in backward order. Channels are looped – #1 goes after #4, and #4 after #1 in reverse.
I’m going to use this device to blow up the fireworks from my flying model or launch “rocket” from the boat. I make home-made detonators from small electric flashlights bulbs for 2.5-3.5V voltage. I cracks bulbs and I coat bulb’s helix with explosive matter from the matches heads, attenuated with few drops of water. The firework’s primer is coated also and connected with the helix till the matter is dried. So, when a channel is turned on, its bulb fires the matter and primer, and after couple of seconds the firework fires too. If you need to drop a “bomb”, you need to hang the firework on some thread, which is tied to the middle of the primer and fixed by drop of flammable glue (CA and liquid glass SiO2 do not match), like polyurethane glue.
Logic of work
Relay can connect one of the four loads to the motor battery. It plugs into one receiver channel and is operating by the following algorithm:
1) When the device initializes, no one channel is active. The device beeps shortly and starts to wait when the stick is neutral. When it got neutral position, it beeps twice more.
2) The device waits in loop, when stick is goes to almost maximum or minimum position;
3) If stick moves to maximum and stays in this position for some time (see constant in the source), the device turns channel #1 on and holds while stick is not in neutral again. The device beeps one time, which means that channel #1 was activated.
4) Moving stick to neutral turns off the channel #1. Next moving to the maximum will activate channel #2 and so on and loop after channel #4. Moving stick to the minimum direction turns channels on in the backward way.
Construction
Power FETs
IRF7311 FETs, used in the device, can pass thru more 10A in short pulse, and about 5-6A continues of current. Ground of the battery and servo cable must be common – and it is so when you use regular ESC with BEC.
Beeps and LED
Beeps are produced by beeper with generator. This kind of beeper eats about 40 mA – it is twice as big as PIC can give. So, if you need a sound acknowledgement of the device operation, you need buffer the PIC output with a FET. I used BS170 FET for this. The LED (if you need it) can be connected to the output pin directly or after buffer (if you have it). If you use 3V sound generator (i.e. HCM1203X) you should connect 50 Ohm resistor in series with it. There is no need in resistor if you use 6V beeper (HCM1206X).
Firmware
You can use PIC12F629 or PIC12C509 with corresponded firmware. PIC12F629 hex file MUST be corrected before burning in: the OSCCAL constant must be changed to your PIC instance value. You should read OSCCAL one byte value from the 3EEh address of PIC factory set memory, open hex file in any text editor, search for A0308316AC and change A0 to your OSCAL value. Save the file and burn it in.
There should be no any changes for PIC12C509 hex file, so it may be easier to use it. Please note, that PIC12C509 is one-time microcontroller, so you can program it only once.
Disclaimer
Use this device on your own risk.
Limitations
Please do not do anything commercial (sale or produce for sale) with it without contacting with me in this thread.