Hi Guys,

I am reading a twenty-year-old electronics textbook that has circuits containing a lamp. The lamp symbol is a circle with a cross through it. Are these
lamps still available today or have things moved on now and they've been replaced ? And if so, what should I buy given that I only build DC circuits with a supply voltage of between +5V and +12V ?

PJ

 

A lamp might be incandescent, fluorescent or LED. I always use LEDs in my projects.

 

Hi Guys,

I am reading a twenty-year-old electronics textbook that has circuits containing a lamp. The lamp symbol is a circle with a cross through it. Are these
lamps still available today or have things moved on now and they've been replaced ? And if so, what should I buy given that I only build DC circuits with a supply voltage of between +5V and +12V ?

PJ

https://www.rapidonline.com/Catalogue/Search?query=mes lamp&tier=E10 MES Lamps
In most cases you could replace them by LEDs, unless it’s in a Wien bridge signal generator.

 

in some versions of oscillator low current lamp was used to stabilize the circuit.
in some cases lamp may be the real or simulated load etc.
why don't you post the circuit? a lot depends on context...

 

Also for industrial electrical circuits that use indicators, the majority are now LED in nature.
Before this, MES incandescent was common.

 

Hi Guys,

I am reading a twenty-year-old electronics textbook that has circuits containing a lamp. The lamp symbol is a circle with a cross through it. Are these
lamps still available today or have things moved on now and they've been replaced ? And if so, what should I buy given that I only build DC circuits with a supply voltage of between +5V and +12V ?

PJ

A circle with an x is not typically an LED light, because LEDs have their own symbol. If your circuit has no way of making 90+volts, it is not likely a neon (generally have their own symbols as well). And generally not a fluorscent because you'll need some portion of the circuit to create high voltage to start the lamp. So, the circuit is likely for an incandescent lamp.
Something like this in 12v.
https://www.parts-express.com/12V-A...0TVG7nVTH0r1q1m5RxjUkD0tCBWpGujQaAneVEALw_wcB

 

If it is just an indicator, the replacement is an LED and a resistor in series.

 

If it is just an indicator, the replacement is an LED and a resistor in series.

... And the industrial panel mount versions come rated for 24vdc and include the resistor internal.

 

Now I remember that when I was very young I used one 12V "gain of wheat" incandescent light bulb in a project about 60 years ago.

 

Hi Guys,

I am reading a twenty-year-old electronics textbook that has circuits containing a lamp. The lamp symbol is a circle with a cross through it.

Any chance you could post a scan or photo of a schematic in the book of interest to you? It'd help to avoid us making assumptions and/or asking further questions.

 

Also in a practical setting, a cross on an indicator light/PB indicates a Disconnect/Lock Function.

 

(Left to right) This is what I recall being symbolic of a lamp. Neon lamp. LED

 

Old Incandescent lamp bulb symbols:

Normally the bulb voltage and part number would be spelled out below the symbol or the symbol in the schematic would have a designation and the parts list would call out the part number and manufacturer. In addition other symbols were used for incandescent bulbs. The bulbs also had a base designation also. Stuff like screw base or bayonet base and all the bases had corresponding designations. Anyway what you describe is a common incandescent lamp (X in circle). The lower bulb in the example may also have a loop rather than what is above. There was likely a half other symbols used for common incandescent lamps.

Are these
lamps still available today

Absolutely. Along with assorted bases. Additionally LEDs (lamps) are available as direct replacements with bases of your choice.

Ron

 

Incidentally the lamp symbol first designated by the JIC in the '50's - '60's for machine electrical schematics/diagrams etc is the same symbol shown for ladder diagram usage today by NFPA79.

 

one 12V "gain of wheat" incandescent light bulb

"Grain of rice" bulb was the more common phrase.
I remember it was for the Weinbridge sine-wave oscillator on an early version of the LM386 datasheet. I think an exact model number lamp was eventually specified.

 

Incidentally the lamp symbol first designated by the JIC in the '50's - '60's for machine electrical schematics/diagrams etc is the same symbol shown for ladder diagram usage today by NFPA79.

View attachment 281981

Max has shown the only symbol that I have seen or used on industrial equipment drawings in the past 50 years. Other symbols may be used in various publications edited by those using pictorial representations. With the JIC symbol a letter designating the display color is often used. The actual light source may vary with the specific application.

 

Over the years I used several but in any drawing I kept all the same for a standard lamp. Most were variations found in ANSI Y32 or IEEE 315 which in some cases parallel each other. The last 25 years I looked at what those who went before me used and used same to avoid confusion among the technicians building and working on the systems. I still have some of my design software,



That "software" was a big improvement over what we had earlier.

Ron