So I have a box of random DHTs that I have never heard before and would like to play around with. I have filament transformers for 1.5v, but nothing for 2.5v or 5v.
Rather than going out and buying a bunch of random filament transformers, is there a more direct, cheap, or easier way to just get the filaments lit for 10-15 minutes so that I can get a sense of what the tube sounds like?
I have thought about batteries or a cheap little external voltage supply.
I know what I am asking for might make some people's skin crawl a bit, but I just want a general impression of what it is I am working with and how I might be able to apply said tubes in interesting ways.
AKA im bored : P
Rather than going out and buying a bunch of random filament transformers, is there a more direct, cheap, or easier way to just get the filaments lit for 10-15 minutes so that I can get a sense of what the tube sounds like?
I have thought about batteries or a cheap little external voltage supply.
I know what I am asking for might make some people's skin crawl a bit, but I just want a general impression of what it is I am working with and how I might be able to apply said tubes in interesting ways.
AKA im bored : P
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You can just rig up something like a simple DC supply with an LM338 and a pot to vary the output voltage. Should be hefty enough for most DHTs. Small batteries won't cut it for anything bigger than a submini.
Now for the opinion part. If you're doing things right, the tubes shouldn't sound like anything. Also, how are you going to turn around a test circuit that fast, are you going to build one circuit that biases the tube in one fixed way, and then plunk each tube in, no matter its design?
Now for the opinion part. If you're doing things right, the tubes shouldn't sound like anything. Also, how are you going to turn around a test circuit that fast, are you going to build one circuit that biases the tube in one fixed way, and then plunk each tube in, no matter its design?
Nah, the design and bias points can change easily enough. I have a giant box of parts, so that really isn't the issue. I even have a small surplus of output transformers.
Its really just power transformers, chokes, and filament transformers I am lacking. And it would just be kind of expensive and a PIA to buy enough of a surplus of power supply iron to simply do some mock bread board designs.
Its really just power transformers, chokes, and filament transformers I am lacking. And it would just be kind of expensive and a PIA to buy enough of a surplus of power supply iron to simply do some mock bread board designs.
Invest in a small variac. Put it on the primary of a 6.3 volt transformer so you can go from zero to about 7 volts. Leave a cheap multimeter wired across the filament pins and set or check the voltage BEFORE installing the tube........45's really don't like 5 volts and I blew TWO of them!
I made a TSE board with jumpers for 2.5 or 5 volts so I could switch from 45's to 300B's.......for got to check....poof.
I made a TSE board with jumpers for 2.5 or 5 volts so I could switch from 45's to 300B's.......for got to check....poof.
I use DC boost modules from eBay. One of them is variable from 45V to 390V, the others have taps. I power them from a 12V SMPS.
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