Recent System Mods
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WSUARC email
Jun 16, 2014, 3:27:00 PM6/16/14
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Jeff,
Can you tell us about the recent mods you did to the repeater? I'm really interested in the LED current sink electronics and the unique DTMF programming circuit.
John
Can you tell us about the recent mods you did to the repeater? I'm really interested in the LED current sink electronics and the unique DTMF programming circuit.
John
Jeffrey Page
Jun 17, 2014, 12:32:40 AM6/17/14
to wsuhams
Macros:
I have programmed two macros for testing purposes.
DTMF 1111 will return the current time.
DTMF 1112 will return the current date.
The LEDs:
I figured out that having the LEDs active would prevent proper operation as the COS signal from the receiver would be expected to sink the entire LED current. I noticed that the COS signal was 1.5V with the RC210 connected, but operated normally (0v) with it disconnected. I built a circuit that operates as a buffer, allowing use of the LEDs. The circuit is plugged into J9 and JP1. If necessary, the original state can be restored in seconds by removing the circuit and replacing the jumper on JP1. I'd have to check my notes for the exact schematic, as the RC210 schematic provided by the manufacturer is not accurate.
DTMF Generator:
Not possessing the programming software, I desired a means programming the RC210 that did not involve transmitting what I was doing to the world. I utilized a headset controller I happened to have on hand. It is unmodified with the exception of a 9V battery connector. The 3.5mm plug that goes to the receiver is instead plugged into the headset controller via an adapter, as the jack is 2.5mm.
The DTMF tones are very low level. To be usable, they will need to be amplified by the following process: Disconnect the COS signal line from the receiver and arrange a convenient means of grounding this signal. Take a small jumper wire with alligator clips or glompers and short R62. This is to increase the gain of U2A. Note the exact position of R60 (Disc #1 In) and then turn it all the way down. Hold down 3 or 5 of the DTMF pad and slowly turn R60 up until the DTMF indicator LED lights up reliably. You can now activate the COS and send tones to the RC210.
To monitor the output without utilizing the transmitter: I used an audio transformer, the one Radioshack sells, and a small speaker. The transformer increased the impedance of the speaker high enough that it could be driven directly by U3A, provided the programming environment did not have significant background noise. Note the position of R47 and then turn it all the way up. Connect the audio transformer between P1TXA and ground.
Cooling fan:
The installed cooling fan had frozen bearings. Dr. Sohl provided a slightly larger one and I will construct a circuit to allow it to be controlled by the fan output of the RC210.
JeffI have programmed two macros for testing purposes.
DTMF 1111 will return the current time.
DTMF 1112 will return the current date.
The LEDs:
I figured out that having the LEDs active would prevent proper operation as the COS signal from the receiver would be expected to sink the entire LED current. I noticed that the COS signal was 1.5V with the RC210 connected, but operated normally (0v) with it disconnected. I built a circuit that operates as a buffer, allowing use of the LEDs. The circuit is plugged into J9 and JP1. If necessary, the original state can be restored in seconds by removing the circuit and replacing the jumper on JP1. I'd have to check my notes for the exact schematic, as the RC210 schematic provided by the manufacturer is not accurate.
DTMF Generator:
Not possessing the programming software, I desired a means programming the RC210 that did not involve transmitting what I was doing to the world. I utilized a headset controller I happened to have on hand. It is unmodified with the exception of a 9V battery connector. The 3.5mm plug that goes to the receiver is instead plugged into the headset controller via an adapter, as the jack is 2.5mm.
The DTMF tones are very low level. To be usable, they will need to be amplified by the following process: Disconnect the COS signal line from the receiver and arrange a convenient means of grounding this signal. Take a small jumper wire with alligator clips or glompers and short R62. This is to increase the gain of U2A. Note the exact position of R60 (Disc #1 In) and then turn it all the way down. Hold down 3 or 5 of the DTMF pad and slowly turn R60 up until the DTMF indicator LED lights up reliably. You can now activate the COS and send tones to the RC210.
To monitor the output without utilizing the transmitter: I used an audio transformer, the one Radioshack sells, and a small speaker. The transformer increased the impedance of the speaker high enough that it could be driven directly by U3A, provided the programming environment did not have significant background noise. Note the position of R47 and then turn it all the way up. Connect the audio transformer between P1TXA and ground.
Cooling fan:
The installed cooling fan had frozen bearings. Dr. Sohl provided a slightly larger one and I will construct a circuit to allow it to be controlled by the fan output of the RC210.
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