How to create a LUT that outputs a signal to a D/A

Why do you need +/-5000V spikes in any way? Design is never without a purpose and signal generation without a reason. Such devices are often in $10k plus range, so what makes you to have one?

The paired spikes that you describe do not resemble what could be generated by a heartbeat of any sort that I've seen, nor do the frequencies fall into a normal range (something like 500 to 20,000 times the frequencies). A v5 or v6 pattern might come closest, but they're still very different from your description. Simple spikes of alternating polarities can be generated without recourse to look-up tables; "qrst" patterns can be obtained in a variety of forms, but the frequencies you're calling for are likely to require something special. Can you tell us why you are calling for a heartbeat pattern, yet providing such completely contradictory descriptions? Can you tell us the purpose (as Shyam has already asked)? Why those specific voltages? How critical is the 0 reference voltage (if it were half a volt, or five volts, or ten, would that present a problem?

Please spell out what you mean by the acronyms LUT and D/A; neither is unique. I'd bet against Light Utility Truck and District Attorney, but then . . . .

Yep,

CRIMINAL

In this case he means Look Up Table, and, Digital to Analogue converter. By heartbeat signal he means something like this:-

OR this perhaps:-

In either case it's really easy to do in excel: the first is an exponential and the second a sine wave.

How accurately do you want the 5000 V signal to track the lower voltage signal. In other words do you really want a look up table and digital to analogue converter: followed by an accurate gain stage. Or will a more general sort of: +ve spike, -ve spike, pause; do.

I agree: CRIMINAL.

Working for the leading manufacturer of electrocardiographs, I had something more like this in mind:

Electrocardiographic recording of the heartbeat.
The QRS complexes represent electrical activation of the ventricles.
The RR interval is the time between consecutive QRS complexes.

Observe that actual heartbeats are far more complex, much less symmetrical, reach vastly lower voltages, and occur in the [roughly] 0.8 to 4 Hz range. [Correction to earlier post: that should have been more like 30,000 to 500,000 times faster - I was thinking of BPM (Beats Per Minute), not Hertz] Of course, this is an idealized version of just one of 12 "leads", and the shapes differ greatly among them. It just happens to be one of the most readily recognizable to most people.

If you want to experiment with a heartbeat pattern you should try to get access to an agilent arbitrary function generator like the model 33220 or one of the former models which may be got more cheaply. They have a pre-defined heartbeat-shape for test purposes which can be changed in frequency and magnitude and you only need an amplifier to generatoe the output.
Regards Uwe

If you intend to create a computer simulation, I can't do nothing for you.

If you want to wire an electronic set, then I can suggest you a simple way.

-1) fabricate a pulses shape (+ and -) based on a + & - 12 Volts shape

-2) If the risetime has not a real importance, arrange the shape to be able to activate 2 each 12V relays during the necessary time to fabricate the +& - 5kV pulses.

-3) arrange the circuit so that the + &- 12V activate the 2 each relays (one after the other)

-4) wire 15 or 20 or more 1N4007 diodes in series, one serie via the anode (+), the other serie via the cathod (-). Amplituide to be measured with a scope.

-5) connect (via the relays), each diodes series to the mains (230Vac-50Hz in Europe, 115Vac-60Hz in USA), each diodes serie going through the relay operated contact (the first relay activated by the + 12V pulse, the other by the - 12V pulse .

-6) Test the circuit in pulse amplitude (5kV), duration. Adjust the 12V shapes if necessary.The amplitude can be measured with a scope (with a sensor divider by 100) to reach the 5kV.

CAUTION: this circuit presents some danger !! Anyway, the 5kV wil produce only microamps current. The 2° danger is the positive ionisation of the air moles. Operate preferably in free air, not in closed room.

Claude Bourdel

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