[转帖]自制心电模拟信号发生器

这是转帖一个德国同行的帖子，用的芯片是4521和4017，很简单。
 


Do-it-yourself

ECG
Patient Simulator

A low-cost solution

created by Frank Weithöner

One of the most important test equipment in the biomedical workshop is the ECG Tester or Patient Simulator. The Patient Simulator is connected to the ECG monitor and delivers the typical ECG signal. Only with such a tester an ECG monitor can be repaired, the functions and alarm settings checked and loose connections of the patient cables be located. A Patient Simulators usually costs several hundred dollars and is unaffordable for small hospital workshop specially in developing countries.
But the realization of an electronic circuit which creates an ECG signal must not be too difficult and expensive. Here I want to introduce you my solution. Only a handful cheap electronic devices are used. No special or exotic IC is needed. All parts should be available in the nearest electronic shop or can be found on old electronic boards from your workshop store.
This circuit consist of a handful electronic devices which delivers a quartz crystal stable ECG signal for 60 and 120 heart beats. Only common electronic parts are needed and the building costs are below 20 $.




Function:

The above shown ECG signal is complex and will be created by different single signals. The P,Q,R,S,T signals are formed in different steps and then are put together in the right sequence. A shift register does the sequence job, RC combinations the frequency and amplitude of the single waves.
IC1 contains an oscillator and a shift register. At the output of pin10 a signal with 16 Hz triggers IC2. IC2 is a counter with 10 outputs. When output 0 of IC2 is active (pin3) the R-C combination R8, C5 creates the P-wave. When the counter jumps to output 3 (pin7) the R-wave is created by R4, C4. The negative part is reduced by the two diodes and simulate the following S-wave. When output 5 is active (pin1) the T-wave is created by R7 and C5. The outputs which are not connected create the needed pauses between the signals. All signals are put together through R3 and R6 which level the respective amplitudes.




When one sequence is finished the shift register stops. Output 9 (pin11) is connected with EN-input (pin13). Only when a reset pulse reaches the counter (pin15) the counter starts again. This reset is also created by IC1. Because in addition to the 16 Hz trigger signal the IC also provides a 1 Hz and a 0.5 Hz signal at pin14 and pin15 which correlate  a heart beat rate of 60 and 120 (switch 2). Therefore the square signal has to be transformed in a positive needle pulse. This is the duty of the combination C6, R11, D4, R10. Because this pulse comes earlier or later (0.5 Hz or 1 Hz) only the lengths of the U period is shorter or longer. The PQRST wave form is not effected.
A small LED D3 with resistor R5 connected to output 3 (pin7, IC2), flashes during the
R- period.
The final resistor combination R12-R15 converts the bipolar signal from the electronic board into the needed three pole output signal.

Note: The circuit is designed for common electronic devices. All parts can be found on old electronic boards or at the nearest electronic shop. But if you have problems to find the clock-crystal of 4.1943 MHz you can take a 4.43 MHz PAL-crystal from a TV. Your output signal is as good as with the clock-crystal but the heart rate will change to 63 and 127 beats per minute.
 




Part list:

R1 = 4K7
R2, R8 = 1M
R3, R4, R9, R10, R11, R12, R13 = 100K
R5 = 1K
R6, R7 = 470K
R14, R15 = 220
C1 = 22 p
C2 = 82 p
C3, C4, C5, C6 = 220n
IC1 = 4521
IC2 = 4017
D1, D2, D4 = 1N4148
cristal = 4.1943 Mhz
D3 = LED 3 mm
2 x IC sockets 16 pin


upload=jpg,6.jpg]UploadFile/2010-2/201022812583335998.jpg[/upload]

有高手请翻译一下

简单译一下给大家参考：

第一段：

在心电图机的测试或一些医学研究场合中，心电模拟器是重要的测试设备之一。这个设备可以像模拟人一样连接到心电监护仪，并提供典型的心电信号。能够用于心电监护仪的维修、报警设置的检验和电缆的测试。这种产品通常需要数百元，小医院和一些不发达地区购置这种模拟器是一种经济上的负担。

但是，用一些电路可以简单制作出模拟心电信号同时比较便宜。在这里，我想向您介绍我的解决方案。只用很少的廉价的常见的电子元件。电路中没有用到特殊的或外来的集成电路。所有器件可以在电子商店或可在旧电路板上找到。 这个电路由很少的器件及一个稳定的石英晶体来模拟60和120心率信号。需要的成本低于20美元（实际上我看甚至低于20元人民币）。

功能：

上图的心电波形表明心电信号是复杂的，由不同的单个波形信号组合而成。P、Q、R、S、T波形是不同的区段按正确的顺序组合在一起。用一个移位寄存器可以完成序列组合的工作。IC1中包含一个振荡器和移位寄存器。在pin10输出16赫兹的信号触发IC2。IC2是一个10位输出计数器。IC2的pin3控制R8，C5创建P波。Pin7控制R4、C4创建R波。用两个二极管模拟出S波。PIN1控制R7、C5创建T波。各信号波形间没有暂停的间隔。所有信号都通过R3和R6控制输出幅度。

第三段主要还是电路原理，说的更加详细。其中对模拟心率的说明似乎和给出的电路有出入。文字说明中IC1的14、15脚用来控制0.5和1hz2种输出，但给出的电路中却是13和14脚。这个需要各位自己验证一下。

最后是一个关于晶振的说明，如果找不到4.1943的晶振，可以用PAL制式电视机的4.43M的晶振，输出波形不变，但心率会变成63和127.

大概的意思就是这些了。水平很差，很多用词可能不准，给大家参考

以下是引用张林清在2010-3-3 9:46:00的发言：

第三段主要还是电路原理，说的更加详细。其中对模拟心率的说明似乎和给出的电路有出入。文字说明中IC1的14、15脚用来控制0.5和1hz2种输出，但给出的电路中却是13和14脚。这个需要各位自己验证一下。

最后是一个关于晶振的说明，如果找不到4.1943的晶振，可以用PAL制式电视机的4.43M的晶振，输出波形不变，但心率会变成63和127.

大概的意思就是这些了。水平很差，很多用词可能不准，给大家参考

利用空闲时间试制中，

据相关资料认为S2应该接14，15脚。现用4.19M晶振，在CD4521 PIN10 测得15.89Hz，PIN13 1.99Hz，PIN 14 0.998Hz，PIN 15 0.499 Hz。

可能是晶振不是4.1943M的原因。

理论值：

PIN 10（Q18）：4.1943*10^6/2^18=16Hz

PIN 13（Q21）：4.1943*10^6/2^21=2Hz

PIN 14（Q22）：4.1943*10^6/2^22=4194300/4194308=1Hz=fPIN13/2

PIN 15（Q23）：..................=0.5Hz

可以了，很准了，示波器本身还有误差呢，这个数据几乎就是理论数据了。把你计算公式中的4.1943改为4.19再算一遍就知道了。

好东西自己试试看

好资料，多谢

很好的设计。

谢谢楼主，你真是急我所急，明天就动手做。

感谢楼主

我也想做做看

真佩服外国的同行！！无语！

有做成功的吗？我也想做！

我也想做个

好贴，技术性强

好东西

原來這個東西可以自己做

这个不错，谢谢了。