Great information, I’ve had one of these for years, actually keep it with my medicine so it’s always with me but wasn’t sure how to use it was was actually guessing it out the best I could!! Thanks again!!
Pretty good. But the fiber moves on electrostatic repulsion rather than any piezo or crystal effect. They used quartz but a carbon fiber can be used as in later models.
An excellent, very informative video. Thank you. One correction regarding oscilloscopes. They certainly can have thousands of volts power supplies, but not at 3 to 4 amps. That would make the oscilloscope a multi-kilowatt device, which it is not.
the charging contact in the pen is a spring loaded contact switch. it also activates when you are pushing down. if you cant get the pen to take a charge take a plastic pen and push on the contact for a few time then retry
What would you recommend as a replacement transistor if the existing one has failed? The manual lists the part as GE 40-16. Is it a General Electric (GE) part or a Germanium (Ge) transistor. I’d appreciate any insights you could provide. Thanks
Have a 750 on the way in the mail to me, with some of the 754 pens, as well as a much rarer CD V-138 pen that has a range of 0-200 milliroentgen for training.
Just got 3 of these pens (2 v-740s and 1 v-730) and a charger but i am unable to see the fiber. Is it possible that it shattered, there is a fair bit of particals on the lenses. Any help would be amazing!
Most likely it has drifted off scale. Press firmly like your charging it and try to adjust the knob clockwise and counter clockwise. The fiber should return within range of the scale. It might take a couple of tries. Good luck.
You can't really fix them, I have saved some in a vacuum chamber but usually doesn't work. Since you know how much it loses in a day, you could still use it knowing the rate of discharge. That number might get worse over time, so you would have to keep checking it over the years.
They are only meant to be used for a short period of time, say a day or less. The model CD V742 shown goes to 200R which wouldn't kill you,, but would likely be sick with radiation poisoning. At 450R exposure you would have a 50% chance of death.
Mine has a germanium transistor in it. Can I switch to a silicon transistor without too many changes? I have a 943/2n1101 transistor in my v756 unit. I haven't found any cross reference to a silicon replacement yet.
Try. It's about the only thing that can go wrong in these chargers. You'll not find any direct replacement for a germanium transistor because they'll work down to lower voltage. But as said try. If it doesn't work satishfactory then try a transistor with higher or lower hFE than the one you first tried. That said you should be able to find suitable germanium transistors today. Mine has an OC83 in it. So if you can't find that exact then try another one with roughly similar data - it really doesn't matter that much. What matters most is that it can handle the power and voltage (voltage is not an issue here as the transistor only experiences 1,5v). OC83 can be easily found on ebay.
The transistor in mine is a CK721 which is one of the earliest experimenters transistors, i would try any low level PNP in it. I would try a 2n3905 - because i have a handful of them. The specs look like it will work.
Oh, boy. You were doing pretty well till you hit 8:30 and then you went off the rails. First your description of equipment from the era shows a complete lack of knowledge. The 220 volts in the dosimeter charger is at a VERY small amperage. It is powered by a 1.5 volt battery. that means this is a 1.5 to 220 volts, a 1 to 145 which means the amperage is miniscule, the CK721 transistor is a germanium that is limited to less than 0.1 amps - above that it smokes. if i divide 0.1 amps by 145 I get 0.0007 amps or 700 microamps. You MIGHT get a shock. Because the oscillator frequency is high - listening to it m it is over 2khz. I would guess that less than .5 Microfarads is enough and that stores nearly nothing. A filter capo needs to store enough during the one half of the cycle to put out enough during the other half. The capacitor will be a low value, not storing much. I own the older model that is point to point wiring. The 900 volts in the Geiger counters is even less dangerous.
Your right on, the equipment isn't particularly dangerous at all however I usually try to avoid liability so saying words like "high voltage" is usually enough to discourage most people unfamiliar with electronics even though the current levels are very very low and the risk of shock is miniscule and might make you say a few choice words at best. If you notice I responded to a few comments years ago regarding electric shock stating the current levels were very low and I wouldn't worry about it. And before you go saying things like lack of understanding, my description of equipment from the era was aimed at equipment from the 20s - 40s, after reviewing it I cant believe I said 50s and 60s. must have had the dates mixed up in my head since most of my electronic equipment is from the second world war.
Great information, I’ve had one of these for years, actually keep it with my medicine so it’s always with me but wasn’t sure how to use it was was actually guessing it out the best I could!! Thanks again!!
Pretty good. But the fiber moves on electrostatic repulsion rather than any piezo or crystal effect. They used quartz but a carbon fiber can be used as in later models.
An excellent, very informative video. Thank you.
One correction regarding oscilloscopes. They certainly can have thousands of volts power supplies, but not at 3 to 4 amps. That would make the oscilloscope a multi-kilowatt device, which it is not.
the charging contact in the pen is a spring loaded contact switch. it also activates when you are pushing down. if you cant get the pen to take a charge take a plastic pen and push on the contact for a few time then retry
What would you recommend as a replacement transistor if the existing one has failed? The manual lists the part as GE 40-16. Is it a General Electric (GE) part or a Germanium (Ge) transistor. I’d appreciate any insights you could provide. Thanks
Thanks! Good educational video
How do I know what type / rating capacitor and transistor to order?
Have a 750 on the way in the mail to me, with some of the 754 pens, as well as a much rarer CD V-138 pen that has a range of 0-200 milliroentgen for training.
Just got 3 of these pens (2 v-740s and 1 v-730) and a charger but i am unable to see the fiber. Is it possible that it shattered, there is a fair bit of particals on the lenses. Any help would be amazing!
Most likely it has drifted off scale. Press firmly like your charging it and try to adjust the knob clockwise and counter clockwise. The fiber should return within range of the scale. It might take a couple of tries. Good luck.
Is there anything that can be done for leaky dosimeters? Maybe put them in a dehydrator a while? Mine is losing about 10 roentgens a day.
You can't really fix them, I have saved some in a vacuum chamber but usually doesn't work. Since you know how much it loses in a day, you could still use it knowing the rate of discharge. That number might get worse over time, so you would have to keep checking it over the years.
I have the same device but have not used it yet, was a little worried about receiving a shock from it. ☺
I wouldn't worry about it, the hv is well contained and this device operates at low current.
@@highvoltagemayhem3345 I have a bad ticker so I'm usually a little more cautious, thanks! 😊👍🏻
Does the cd v-717 have high voltage as well? And do you have to discharge it even to just install a battery?
How much the charge will laston the diosemeter meter.
And whats the safe range
Ratogens??
Sorry for my bad english
They are only meant to be used for a short period of time, say a day or less. The model CD V742 shown goes to 200R which wouldn't kill you,, but would likely be sick with radiation poisoning. At 450R exposure you would have a 50% chance of death.
So do wear it in a shirt pocket?
Mine has a germanium transistor in it. Can I switch to a silicon transistor without too many changes? I have a 943/2n1101 transistor in my v756 unit. I haven't found any cross reference to a silicon replacement yet.
Try. It's about the only thing that can go wrong in these chargers. You'll not find any direct replacement for a germanium transistor because they'll work down to lower voltage. But as said try. If it doesn't work satishfactory then try a transistor with higher or lower hFE than the one you first tried. That said you should be able to find suitable germanium transistors today. Mine has an OC83 in it. So if you can't find that exact then try another one with roughly similar data - it really doesn't matter that much. What matters most is that it can handle the power and voltage (voltage is not an issue here as the transistor only experiences 1,5v). OC83 can be easily found on ebay.
The transistor in mine is a CK721 which is one of the earliest experimenters transistors, i would try any low level PNP in it. I would try a 2n3905 - because i have a handful of them. The specs look like it will work.
Do you know what voltage the lamp runs on if it needs replaced?
It's a 1.3Volt 0.1Amp #131 screw type flashlight bulb. You should never have to change it, but if it goes bad he showed you the spare bulb inside.
@@ForbiddTV i believe in being prepared. My spare was missing on mine. Thanks for the info on the bulb.
can i somehow do this without a charger
No
@@ForbiddTV yeah i got a charger but it keeps shocking me everytime theres a battery in
How do I remove the spare bulb
It's real tight in there. Try unscrewing it while pushing from up from the bottom with something like a butter knife.
Variable "transformer" - no, potentiometer. A variable resistor.
Oh, boy. You were doing pretty well till you hit 8:30 and then you went off the rails. First your description of equipment from the era shows a complete lack of knowledge. The 220 volts in the dosimeter charger is at a VERY small amperage. It is powered by a 1.5 volt battery. that means this is a 1.5 to 220 volts, a 1 to 145 which means the amperage is miniscule, the CK721 transistor is a germanium that is limited to less than 0.1 amps - above that it smokes. if i divide 0.1 amps by 145 I get 0.0007 amps or 700 microamps. You MIGHT get a shock. Because the oscillator frequency is high - listening to it m it is over 2khz. I would guess that less than .5 Microfarads is enough and that stores nearly nothing. A filter capo needs to store enough during the one half of the cycle to put out enough during the other half. The capacitor will be a low value, not storing much. I own the older model that is point to point wiring. The 900 volts in the Geiger counters is even less dangerous.
Your right on, the equipment isn't particularly dangerous at all however I usually try to avoid liability so saying words like "high voltage" is usually enough to discourage most people unfamiliar with electronics even though the current levels are very very low and the risk of shock is miniscule and might make you say a few choice words at best. If you notice I responded to a few comments years ago regarding electric shock stating the current levels were very low and I wouldn't worry about it. And before you go saying things like lack of understanding, my description of equipment from the era was aimed at equipment from the 20s - 40s, after reviewing it I cant believe I said 50s and 60s. must have had the dates mixed up in my head since most of my electronic equipment is from the second world war.
Arkie Shibley is that you?