LED高手进，这个能改成1602显示吗？

968201

福禄克8050A的屏，通病就是一段时间后就会变黑，现在网上有人改LED的，有谁能改成1602来显示？









Fluke 8050A LCD display replaced with LED seven-segmentRecently I was able to cheaply buy a second hand Fluke 8050A made in the early eighties. It is a nice 4.5 desktop digit meter, but a typical problem seems to be that the LCD wears out and goes black. Replacement LCD displays are hard to find, not cheap and probably lead to similar problems in due time.
The LCD display is interfaced by standard components (CD4054 and CD4056) that drive each segment individually. This allows it to be replaced with a LED 7-segment display. However LCD displays are driven normal/inverted about 30 times/second. LED displays can be used by disabling this clock and connect it to a fixed level (high).
Since my Fluke does not have the battery option I was pretty confident that the power supply would be able to provide the additional LED current. The LCD drivers are able to sink current per segment in the order of 2mA. Sinking capability is somewhat higher than sourcing, so I decided on an LED display with common anode.
Since I had no idea how bright a LED display is with this amount of current, I ordered the brightest 9mm displays I could find. If they turned out too bright I could always reduce the current. And that is what happened. In the end a series resistor of 2k2 showed proper results. With 1k the display was brighter, but some bleeding to neighbouring segments started to become noticable.
The LCD display also has a couple of special symbols for high-voltage(HV), low battery(BT), decibel (dB) and relative measurement (REL). Of course these have to be handled differently and I simply printed them as inverted text on paper. The paper is then lit from behind with separate high bright LEDs. I blackened the laserprinter output a bit more with a felt pen.
Another special case is the plus (+) and minus (-) of the LCD display. Personally I do not see the need for a plus symbol, so I decided to use the minus only since the LED can provide this nicely. The most significant digit segment g is used for this purpose. To “disconnect” it from the digit I tipped a small peace of the segment with a black CD felt pen.
However the behaviour of the +/- signals is a bit strange. I have no knowledge of how this worked originally on the Fluke. After playing around what seemed to work in all measuring modes (R/V/A/dB and REL combinations) is to use the inverted '-' signal and disable the segment when '+' is high (??!!). Without using the '+' signal, measuring ohms has the minus sign always on. Oh, well, this can all be done using a single small BS170 mosfet.
Below is shown the detailed images of the whole process, the circuit diagram of the display board and the circuit modifications.

The new LED displays in stages

登录/注册后可看大图 The bad LCD display	登录/注册后可看大图 Replaced it with 9mm LED displays and 3 LEDs
登录/注册后可看大图 With printed symbols on paper	登录/注册后可看大图 Paper is made more black with felt pen

The selected LED display details:
Kingbright SA36-11SRWA
Red 9mm display
Common anode
Brightness 2200-9000 uCd @ 10mA
Conrad order code: 158780
Dimensions:

                               
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The Fluke 8050A display board circuit (photo)

                               
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Circuit modifications:

                               
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Note that each individual segment has a 2k2 resistor between it and the driver pins. I soldered the cut resistors directly to each driver IC and wired them from there to each segment. This was a bit more work then I expected... The symbol LEDs have 1k in series. For a Fluke with the battery option you would need an additional LED.

The results:

                               
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Further ideas RS-232 interace:
Now I understand the circuit en have seen the signals on an oscilloscope, I was thinking of making an isolated RS-232 interface to this meter. It is a desktop model that is mains powered, so keeping it switched is not a problem. This would allow long duration measurements like rechargable battery charge/discharge curves etcetera. To isolate the circuit to be measured from the computer would also require an opto isolated interface. It might never happen, but if it does I will update this page.

968201

福禄克8050A液晶显示器所取代，带LED七段最近，我能廉价购买二手福禄克8050A在80年代初提出。这是一个很好的桌面4.5米位，但一个典型的问题，似乎是在LCD磨损和变黑。更换液晶显示器很难找到，不便宜，可能会导致在适当的时候类似的问题。该液晶显示器是由标准组件（CD4054和CD4056），该驱动器每一部分单独接口。这使得它与一个LED 7段显示器取代。不过液晶显示器驱动正常/反向约30次/秒。 LED显示屏可以使用禁用此时钟，它连接到一个固定的水平（高）。
自从我福禄克没有电池的选择，我非常有信心的电力供应将能够提供额外的LED电流。在LCD驱动器能够吸收每段电流的二毫安秩序。沉能力略高于采购，所以我在与共阳极LED显示屏决定。因为我不知道如何明亮的LED显示屏是最新的，我命令最亮的9毫米显示我能找到这样的数额。如果他们原来太亮我总能减少电流。这就是发生的事情。在年底2k2串联电阻显示正确的结果。随着经销商显示了光明，但一些人在附近部分出血开始变得更为明显。

该液晶显示器也有一个高电压（HV），低电压（BT）的特殊符号的情侣，分贝（dB）和相对测量（REL）。当然，这些要处理不同，我只是印在纸上的文字倒他们。该文件，然后从后面点燃有独立的高亮度发光二极管。余败坏了激光打印机的输出一点的笔尖。另一个特殊情况是加号（+）和减号（ - ）的液晶显示屏。我个人不认为一个加号的需要，所以我决定只用减去自发光二极管可以提供这样很好。最重要的数字段克是用于这一目的。以“断开连接数字我倾斜的黑色CD一小部分的和平”它觉得笔。然而，在+ /行为-信号是有点奇怪。我并不知道如何工作的福禄克原本。经过玩弄什么似乎在所有测量模式（注册商标/视频/阿/分贝以及Rel组合）是使用倒' - '的信号，并停用部分在'+'高(??!!).不使用'+'的信号，测量欧姆有减号始终。噢，这可以全部完成使用单一小BS170 MOSFET的。下面显示整个过程的详细图像，显示板的电路图，电路修改。

暗夜迷影

只有想不到，没有做不到，等高手上

gjs

这和1602的显示原理不一样吧?1602是字符的,这是笔段的......

gjs

或者用1602模拟笔段?{:1_217:}

圣龙

好象难度不小

gjs

好象有兄弟用1602模拟成单排的笔段过,俺当时觉得不好看没注意......

wooz

要用1602，看来得上一片单片机做信号采集和显示

yanjian

用单片机的话,直接改成12232好了

灯泡企鹅

记得有烧基准的高手把8840的屏换成点阵LCD的，也用了一片AVR。