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About FireFly

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  1. I started collecting the parts for this project quite some time ago and then got sidetracked with other things.
  2. Anyone happen to have a pcb image for this project that they would like to share? Thanks.
  3. I was looking at the datasheets for the Maxim ICL7135 4 1/2 Digit ADC and the ICM7211 4 Digit LCD Decoder Driver: http://pdfserv.maxim-ic.com/en/ds/ICL7135.pdf http://pdfserv.maxim-ic.com/en/ds/ICM7211-ICM7212.pdf I'm still a little (actually alot!) baffled by the various display interfaces but I was wondering if 2 separate meters (a volt meter and an amp meter) were created using 2 each of the 7135/7211 chips, could they be connected to one LCD display such as a 1 line, 16 character display to show volts and amps at the same time? Or am I trying to put a square peg in a round whole? :-\
  4. Sorry about my 2 previous posts. Please ignore my stupidity. I'm going back to bed now!
  5. Sorry. My last post should have said 450v caps rather than 250V caps.
  6. I'm aware that the filter cap is recommended to be much larger uF wise but I'm wondering about the voltage rating. The original part list called for a 50V cap. I may have found some large-enough, 250V caps. Would using caps with much higher voltage ratings do anything good or bad to this power supply? Should they perform as well as the same size cap rated at 50V? There must be some kind of trade off. Perhaps physical size or cost?
  7. And one more substitution please: 2N2219 I can't seem to locate these in a form easily attachable to a heat sink. Can someone suggest another model(s) suitable for this circuit that would be easier to find in a "heat sink form" such as TO-220? Thanks again (for the umteenth time!)
  8. Could some one tell me if TI's 44V TLE214x op-amps would also be a good substitute for the TL081. I haven't got a complete handle on what all the specs mean yet. Thanks. Datasheet: http://focus.ti.com/lit/ds/symlink/tle2141a.pdf
  9. Thank you, MP. Sounds like 3/4 experience and 1/4 mathematical. The heat sink(?) I was referring to in the picture is the black "collar" towards the upper right of the board right beside where the 3 2N3055 connection wires attach to the board. Isn't that the Q2 = 2N2219 and a little, round, black heat sink or is it something else? That's what made me wonder in the first place about knowing when to use a sink especially if only working from schematics. As far as heat sink ratings, I guess I should pay more attention to what was attached to old heat sinks that I salvage to give me a hint of
  10. I was looking at various datasheets for bridge rectifiers for the "0-30 VDC STABILIZED POWER SUPPLY" project. I'm trying to understand when a heat sink is required. For example, the datasheet for the NTE5329, 6A bridge rectifier: http://www.nteinc.com/specs/5300to5399/pdf/nte5329_31.pdf ...states "Recommended mounting position is to bolt down on heatsink with silicone thermal compound for maximum heat transfer with #6 screw." But how big a heat sink does it need? Is there any way to tell from these spec sheets (bridges, transistors, etc.) if my usage is low enough to not require a sink?
  11. Does this NTE cross reference give you what you want: http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?OpenForm It comes up with an NTE equivalent for each one you listed and maybe you can get the specs from the NTE part datasheets? Does that help? Sorry if this isn't what you wanted. I'm still learning this stuff.
  12. I've been looking into selecting a one-piece square bridge rectifier for the 30V/3A power supply project. There seems to be lots of these like every other component type! Generally, they seem to have rather heavy voltage/amperage handling abilities. What is the downside to using a bridge with significantly higher ratings than required besides slightly higher cost and larger physical size? Would a bridge with just adequate specs put out more heat than one with much greater than required specs?
  13. While looking over some big capacitor specs on the NTE site, I came across what they call Snap-in mount. Can these be used with a board I create myself? Is there some kind of connector that I would attach to the board and then the capacitor attaches to that? Or what...?
  14. I've almost collected all of the parts I need for the original 30V/3A project. A new, old-stock, Hammond 25V/5A transformer will be arriving any day now. I've got the presinsitized board, chemicals, etc. and have added extra points to drill to allow meter attachment (someday!). But I don't want to burn it until all of the components have been suitable "upgraded". Could someone suggest what part to use for the diode bridge upgrade? The PCB appears to have enough room on that corner to easily allow changes to the copper trails for this if needed. Can the 1N5402,3,4 diodes just be upgraded
  15. Thank you very much for your previous posts on the component sizes and issues. I just want to make the original 30V/3A supply reliably live up to its specs! Just so I understand would you please answer the following. For the original 30V/3A supply: Transformer should be about 4A to 5A, right? Do you feel that "C1 = 3300 uF/50V electrolytic" is suitable? If not, what would you recommend? Are the "1N5402,3,4" diodes adequate for the bridge? Any other substitutions you would recommend? Thanks alot.
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