Finding new Light bulb

[mozart1973]

Need a new light bulb. The old one is a philips 8005/71.



It doesn't say what voltage and amps on it.

Where can I find one like this or similar?

 

[tpetar]

Can be 18V 0,1A thats for 8005D.

Where this bulb is used in which socket, can you measure voltage in that socket?

Is this bulb for position lights in some car-truck ?



Its interesting when Philips made TLED with over 200lum/W to see something like this.

 

[mozart1973]

Can be 18V 0,1A thats for 8005D.

Where this bulb is used in which socket, can you measure voltage in that socket?

Is this bulb for position lights in some car-truck ?



Its interesting when Philips made TLED with over 200lum/W to see something like this.

No, it is one of two bulb for lighting the scale on an old radio. It is difficult the measure inside those small sockets.

 

[tpetar]

Old radio works on batteries or mains voltage?

Then can be lower voltage something like 3 - 6V.

You can measure voltage from bulb socket.

 

[mozart1973]

230 volts AC.

 

[tpetar]

Ok but bulb probably works on lower voltage, I just supose, but should be careful. Do you have some photo of device inside?

 

[chuckey]

the scale lights for a valve radio are either 6.3 V and are wired in with the heater supply or are .1 or .3 A and are wired in series with the other series wired valve filaments. For long life the 6.3V fed bulbs can be rated at 7V.
Frank

 

[mozart1973]

Yes, here is one.

https://obrazki.elektroda.pl/1391503800_1366392363.jpg

 

[tpetar]

You can easily check connections of bulb socket where they go, additional I will check voltage with voltmeter, starting from 250V AC range.

 

[mozart1973]

I tried testing the voltage. In dc it reads zero but in AC it reads about 40 volts. And that is when the radio is warmed up. Untill then it reads almost 250v and dropping to 40 when warm. Can that really be true?

I also tried putting dc through the working bulb and about 10 volts made it glow as it does on the radio. So is it 10 volt dc or 40 volt ac bulb.

If I only had the schematics....

 

[tpetar]

That I feared, that bulb can be 220V.

From posted picture, bulb socket is in middle with that black part soldered on back side?

 

[FvM]

I also tried putting dc through the working bulb and about 10 volts made it glow as it does on the radio. So is it 10 volt dc or 40 volt ac bulb.

An incandescent lamp doesn't care for AC or DC. If it's for 10V DC, then for 10V AC as well. You measured the voltage with the lamp in place?

 

[mozart1973]

Yes, but can't tell what that black part is.

- - - Updated - - -

An incandescent lamp doesn't care for AC or DC. If it's for 10V DC, then for 10V AC as well. You measured the voltage with the lamp in place?

Both. With lamp it was a little less than 40v.

 

[D.A.(Tony)Stewart]

It probably runs of the vacuum tube filament ac voltage with some voltage drop in the series resistor. 12v for example. You could remove the glass and install two LEDs of any colour back-to-back with a large resistor in series external according to the voltage you measure and glue the parts with hotglue together. In the base. Choose red or blue for fun. Series R for 20mA . If 24V, then choose consider voltage drop and 50% duty cycle .

 

[chuckey]

Some AC/DC sets run their filaments in series at 100 mA or 300mA ( UXXX tubes or PXXX tubes). In series with the chain is a thermister that has a high resistance when cold and a low resistance when hot. It looks like your bulb is connected across part of this chain.the effect would be that the set would take a long time to "warm up" without the bulb and its filaments would be running at a lower current. Also as the bulb is connected across the thermistor it would actually suffer an overload when the set is switched on from cold. What are the tube (valve) types used in the set?
Frank

 

[mozart1973]

They are

UCH81, UF89, UBF89, UCL82 and UCC85

 

[D.A.(Tony)Stewart]

If you measure the open circuit voltage on the bulb and the series resistor attached.

If they put all in series then some would be very dim and others too bright until they all reach thermal equilibrium.

UCC85 Vf 26 Volts / If: 0.1 Ampere 2.6W
UCL82 Vf 50 Volts / If: 0.1 Ampere 5.0W
UBF89 Vf 19 Volts / If: 0.1 Ampere 1.9W
UF89 Vf 12.6 Volts / If: 0.1 Ampere 1.2W
UCH81 Vf 19 Volts / If: 0.1 Ampere 1.9W

You can experiment and guess watts and volts to find the missing link light bulb or shunt the string to replace the missing bulb with a 12V Xmas light or use LEDs as I suggested. Then use an amp meter to verify current is 100mA AC or DC for the filaments if connected.

 

[mozart1973]

THey don't all seem to glow evenly much when warm. I'll try with a 10-12v light first if I can find one that has the same size as the old one.

 

[FvM]

12V/100mA and 18V/10mA E10 socket have been popular indicator lamp forms and are still available at well-assorted distributors and DIY shops.