Taz
Harmless
Posts: 9
Registered: 5-3-2005
Member Is Offline
Mood: No Mood
|
|
Power Cord
I recently went to a garage sale and found one of these
http://www.labequip.com/catalog.php?stkno=18210
for $10.00 looks brand new though it doesn't have a power cord also it has variac
only writen on it does this mean I am going to have to buy a variac transformer to operate this it does have a dial for temp control.Does
anyone know where to get a power cord or any thing else about it . Thanks
|
|
|
mick
Hazard to Others
Posts: 338
Registered: 3-10-2003
Member Is Offline
Mood: No Mood
|
|
I would guess that it depends on the age. The old heating mantles were a bit sparky because of the electrics and could over heat when they burnt out.
The ones around today seem better than the stirrer / hotplate with an oil bath.
mick
|
|
|
runlabrun
Hazard to Others
Posts: 172
Registered: 4-12-2004
Member Is Offline
Mood: No Mood
|
|
you went to a garage sale and got a heating mantle??!?!?!?!
DAMN YOU!
-rlr
|
|
|
Taz
Harmless
Posts: 9
Registered: 5-3-2005
Member Is Offline
Mood: No Mood
|
|
It was more like an estate sale but I figure same thing
I have been looking into ot though I need a variac power supply I slowly increase voltage to increase the heat as for as a cord goes I guess I could
make my own its a pretty nice mantle scince it will hold a variety of flask sizes
[Edited on 10-4-2005 by Taz]
|
|
|
neutrino
International Hazard
Posts: 1583
Registered: 20-8-2004
Location: USA
Member Is Offline
Mood: oscillating
|
|
A simple light dimmer spliced into the power cord should work just as well. It works for me, anyway.
|
|
|
MadHatter
International Hazard
Posts: 1346
Registered: 9-7-2004
Location: Maine
Member Is Offline
Mood: Enjoying retirement
|
|
Heating mantle
I'm still looking around for a decent power supply for my 2 heating mantles. They came
with a set of lab glass that I bought on eBay.
From opening of NCIS New Orleans - It goes a BOOM ! BOOM ! BOOM ! MUHAHAHAHAHAHAHA !
|
|
|
neutrino
International Hazard
Posts: 1583
Registered: 20-8-2004
Location: USA
Member Is Offline
Mood: oscillating
|
|
Again, I advise a dimmer switch. Just make sure that they're rated at or above the mantles.
|
|
|
Quince
National Hazard
Posts: 773
Registered: 31-1-2005
Location: Vancouver, BC
Member Is Offline
Mood: No Mood
|
|
You can make a variable AC supply quite easily. Get an optoisolated, AC capable solid state relay (or make one from low Ron MOSFETs), and drive it
with a PWM. If you add an LC filter to the output, you can drive anything that needs whatever AC voltage up to the outlet's 120V. This is a
fraction of the cost, and tiny fraction of the weight, of a variac; efficiency is usually on the same order or better.
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
|
|
|
unionised
International Hazard
Posts: 5128
Registered: 1-11-2003
Location: UK
Member Is Offline
Mood: No Mood
|
|
"You can make a variable AC supply quite easily. Get an optoisolated, AC capable solid state relay (or make one from low Ron MOSFETs), and drive
it with a PWM. If you add an LC filter to the output, "
Or buy a dimmer.
|
|
|
Quince
National Hazard
Posts: 773
Registered: 31-1-2005
Location: Vancouver, BC
Member Is Offline
Mood: No Mood
|
|
Yeah, but a dimmer doesn't put out a nice sine waveform. A lot of equipment, especially if it has a transformer, won't work with dimmer
output.
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
|
|
|
12AX7
Post Harlot
Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline
Mood: informative
|
|
A dimmer into a transformer into a resistive load is fine.
Tim
|
|
|
Quince
National Hazard
Posts: 773
Registered: 31-1-2005
Location: Vancouver, BC
Member Is Offline
Mood: No Mood
|
|
Other than lights and heaters, what is a resistive load?
BTW Tim, for filtering the output of a PWM sampled AC mains, how do I calculate the inductor? Of course I can use the simulator and guess/try values,
but obviously that's the dumb way to do it. I know that higher switching frequency needs smaller inductor, but there's a limit to how fast
the SS relay can switch. Also, what frequencies are more/less likely to cause interference with other things on the circuit/nearby? Finally, I
assume a slow-blow fuse should be used?
[Edited on 1-5-2005 by Quince]
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
|
|
|
unionised
International Hazard
Posts: 5128
Registered: 1-11-2003
Location: UK
Member Is Offline
Mood: No Mood
|
|
"Other than heaters" is off topic.
Any purely reactive load isn't doing anything (no transfer of energy) so, to a greater or lesser extent, all loads are resistive.
I'm not sure I agree with your definition of easilly.
The cut-down description of the technique runs to a couple of lines and has already sparked questions.
Designing solid-state transformers is really quite involved, particularly when you want them to behave themselves with very inductive loads.
|
|
|
Archimede
Harmless
Posts: 33
Registered: 13-5-2005
Member Is Offline
Mood: No Mood
|
|
If it was me, I would inspect the inside of the mantle to see if it's just made of the heating element without any other electronic part.
An heating element is just a resistor and it shouldnt be sensitive to the wave form of the electricity . Just make sure the machine is rated to work
with 115V or so. If this is the case a dimmer switch should be just fine and before you turn it on make sure the dimmer is set very low and increase
gradually to experiment the results.
Also, looking at the link it seems that there may be 2 different heating elements and/or some additional resistor to half the power output (150/300W).
[Edited on 12-6-2005 by Archimede]
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
