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 Adding LED's to this circuit for trip failure ID?? 
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Post Adding LED's to this circuit for trip failure ID??
I have a working version of this circuit I built some time ago. Instead of the center tapped transformer I use two 50V, 40 or so Amp computer server switch mode power supplies in series, for a fully regulated 100V to the Class D FET's, and a separate linear regulated 12V DC supply for the rest of the circuitry.

I have shown the state of the gates used for over current protection to the PA FET's, excess reflected power from the SWR bridge, and loss of the 272kHz input signal with the amplifier working normally, on an abridged schematic showing the amp in the form I am using it. I also attach the originator's build documentation, but note I deleted some early circuitry as I already had a suitable (Kenwood TS-590 1mW exciter at 136kHz), and a pre amp and frequency doubler to feed my abridged circuit at 272kHz.

As it stands a single LED shows if the circuit has gone into fault mode, due to high reflected power, too much PA current, or no input signal. I am rebuilding the amp mechanically to give much easier access for maintenance and repair, and would like 3 separate LED's to show just which of these three faults tripped the amp.

IC6 has a spare trio of input pins and an output pin, and IC1B has 3 dual inputs unused.

Can anyone much cleverer than I see a way to have 3 separate LED's showing just which of the three possible fault states tripped the amp please?


Finally, am I right in thinking that diode D3 is there to stop voltages above about 12V reaching the gate pin 13 of IC1B, if the SWR bridge got really excited with reflected power? If not, what is its function?

Thanks.

Amp documentation: http://www.gatesgarth.com/amp.doc

Current circuitry schematic: http://www.gatesgarth.com/136bigv2mods-2.jpg


Sun Nov 13, 2016 12:07 pm
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 Adding LED's to this circuit for trip failure ID?? 
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Post Re: Adding LED's to this circuit for trip failure ID??
Have a look at the attached schematic.

You can pick up the required alarm signals from the existing circuit as I have show at the left hand side of the schematic.

Use a 4096 to provide a buffer and LED driver to drive the three LEDS for individual indications of Drive Signal Fail, High VSWR and High Current.

The 4096 has six inverters, we are using only three of them. The unused inputs should not be left "floating", so connect the unused inputs to 0v as shown.

While we are considering floating inputs, you have created such a situation where you feed the drive signal into IC3 and IC4 via a 10nF capacitor. It would be a good idea to connect IC3 pin4 to the 0v line via a 10k resistor, in order to give it a DC reference point.

Jim GM3ZMA


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Mon Nov 14, 2016 9:20 am
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 Adding LED's to this circuit for trip failure ID?? 
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Post Re: Adding LED's to this circuit for trip failure ID??
Sincere thanks for taking the time to do a very professional looking schematic and reply to my somewhat complex question!

I have two more based on your answer. I think a typo was introduced into your reply, it's usually myself who is expert at those ;)

I assume the schematic is correct and I need to use 4069's and not 4096 devices?


I also am not sure about how the normally Low signal to IC1 Pin 13 would cause the LED to be off? Is that pin actually held Low or HIGH? The function of D3 escapes me, being a lowly 2E0 ;) It wouldn't really matter if I knew that the LED should normally be ON for that pin. The devices I can find are 4069 suffix "U" which appears to mean UNbuffered. Is that a problem? You show 4069 "D" on the schematic, i don't see those in the marketplace...


Again, VERY much appreciated Jim, most helpful!!! Thanks and 73 from 2E0ILY.


Mon Nov 14, 2016 2:39 pm
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 Adding LED's to this circuit for trip failure ID?? 
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Post Re: Adding LED's to this circuit for trip failure ID??
Quote:
I assume the schematic is correct and I need to use 4069's and not 4096 devices?

Yes a CMOS 4069 Hex Inverter.

Quote:
I also am not sure about how the normally Low signal to IC1 Pin 13 would cause the LED to be off?

Well spotted! The fresh faced 2E0 finds the wizened old G3s mistake! :)
I can think of at least two ways around this,
The simplest one to describe in words would be to connect one of the spare inverters between pin4 of IC9 and R2.

Quote:
The function of D3 escapes me

It is just there as a voltage limiter.
As the reflected power increases, so the voltage from the SWR bridge will increase, what you don't want is the signal voltage into the CMOS gate rising way above the supply voltage.
As the voltage at the anode of D3 rises above 12.6 volts ( 12v supply + 0.6v forward volt drop in the diode) the diode will conduct and as the signal is coming through the 47k resistor, the excess voltage from the SWR bridge will be dropped across the resistor.

Quote:
The devices I can find are 4069 suffix "U" which appears to mean UNbuffered. Is that a problem?

No that will be fine.

Quote:
You show 4069 "D" on the schematic,

Just the device which was easy to grab in the schematic drawing program (Eagle) which I used.

OK?

Any more questions, just let me know.

Jim GM3ZMA


Mon Nov 14, 2016 4:05 pm
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 Adding LED's to this circuit for trip failure ID?? 
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Post Re: Adding LED's to this circuit for trip failure ID??
Jim, that's perfect, just what I needed, I cannot thank you enough, you went to great trouble and it is appreciated! :)


Mon Nov 14, 2016 5:03 pm
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