To conclude this article, Figure 20 shows a simple way of fitting an alarm-driving over-range switch to a bar-type LMseries LED-driving indicator circuit. This establishes power to the chip. Konstantin Dubovenko 76 5. Now you can add the switch. By adjusting VR1 appropriately we get 1. Figure 13 shows a very useful modification which enables the above circuit to be powered from unregulated supplies within the 12 to 18 volt range.

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It helps to hold them in place at one end with something like PVC tape or they jump around like crazy.

Thus, when Rx is zero, FSD is 1. You just solder it from the top, using fine cone tip. The potentiometer we will use can really be of any value. The load resistance put on pin 7 will control the Lm39144 brightness – hence a 1K0 R2 is connected to ground.

The left one looks like it is for a capacitor 2. Dot mode only lights up a single LED at a time.

Tag: Bar Graph Volt Meter Range 0 to 10v using LM3914

An alternative variable-range 1. V- braph the negative terminal of your power supply. Tying this pin to mV or less ensures “dot-mode” where only 1 LED is on at a time.


Use a cheap 10x resistor network of 10Kilo ohm to pull up all outputs of LM when connecting it to logic gates. One way of achieving this is to solder a SMD resistor as shown by the yellow line:. grapu

Figure 12 shows another way of obtaining a bar display without excessive power dissipation. For substantially lower full-scale RPM values, the C2 value may have to be increased — the value may have to be reduced on vehicles with six or more cylinders.

Assembly tips MarkU suggests taking a break every 10 seconds when soldering the IC in order to let the internals cool down. Bar mode is a mode in which if full voltage is going to the chip, all 10 LEDs will be lit up. The LM does this also. The left-hand variable resistor requires similar treatment under the switch.

How to Build an LM Dot/Bar Display Driver Circuit

I think the gist of all of these answers is that you have to favor whichever of the two parts LED array or LM is most susceptible to heat damage. Since you have a DIP chip LM you can solder ba chip pins directly into the vias from the chip side.

I found it easier to solder from the component side as the legs did not protrude very far through. For many years, the best known ICs of this type were the U etc.


If 5 LEDs are lit, this could mean it’s at half strength. I would solder the IC legs between the led display first. Resistors must be chosen to set the Vout node to the proper voltage and also scaled to get the current limit you desire. Learning Electronics Need to brush up on your electronics principles?

Many suitable circuits are published in op-amp application manuals and circuit reference books and encyclopedias, etc. So is there some trick to soldering this together?

How to Build an LM3914 Dot/Bar Display Driver Circuit

Without datasheets, my guess would be the LED array’s filler compound is braph likely to melt first. When I opened it up I saw a board like this: How the Circuit Works The potentiometer is the mainstay of the circuit. Why do you say “opamp used as comparator” instead of “comparator”?

They might well be real comparators, the symbol is the same. Recheck the settings of RV1 and RV2. But you’ll have to use your best judgement.

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