Helix HX-4700 back on the bench
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Old school Scott
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I have learned so much by reading these comprehensive disruptions of your boombox hotroding. Thanks for breaking it down for us.
Cheers OSS
Cheers OSS
Chris,
The 78xx series regulators are linear regulators. They do a great job but for the simple task of powering LED's, which don't really care if you get clean or crappy power, I suggest you instead get yourself some buck regulators. They work like switching power supplies and are very efficient compared to linear regulators.
As for use, keep in mind that the amount of power dissipated is based on the difference between the input and output voltages. The higher the input voltage, the greater the amount of power wasted and here's why:
Suppose you have 18v in and 15v out. That is a 3V voltage drop. Current is, for the sake of this example, an arbitrary 300mA. The amount of power dissipated will be 3V x 300mA or 900mW (ALMOST 1 watt). Now, lets say you upped the voltage to 27 volts. You now have 12V x 300mA (the current stays the same regardless of input voltage). So in this case, 12V x 300mA = 3,600mW. OMG, you are now wasting over 3-1/2 watts of power. As 9V batteries are quite expensive and have very low AH ratings, it's fair to say that the more power you throw at it, the more power will be completely wasted. In other words, because current remains the same regardless of input voltage, the greater the voltage drop required for your regulated output, the greater the amount of power dissipated. Also, to be stable, on these type of regulators, the input voltage needs to be higher than the output voltage. I forget how much but it's like 1.2 or 1.5 volts. That is the headroom needed. That means that you are always wasting some amount of power. I realize that you don't want to redo your circuit but for reasons of efficiency, especially when it comes to those LED's, it's best to plan the voltages required by arranging them in a parallel/series array so that a minimum of current dropping resistors are required. Or how about just rigging up 15v with AA or AAA battery holders? The pack will be bigger than the 9V batteries but those batteries are a ton cheaper and will last much much longer AND no regulator required! I'll bet you anything that even if you fed it 12v (8 cells instead of 10), that the LED's will still light and the difference in brightness might not even be noticeable. Saves you 2 more cells, less current consumed, and a smaller pack to boot. Try it, you'll see.
So with respect to your "new" project which requires a 3v regulator...... do you see where I'm going with this?
The 78xx series regulators are linear regulators. They do a great job but for the simple task of powering LED's, which don't really care if you get clean or crappy power, I suggest you instead get yourself some buck regulators. They work like switching power supplies and are very efficient compared to linear regulators.
As for use, keep in mind that the amount of power dissipated is based on the difference between the input and output voltages. The higher the input voltage, the greater the amount of power wasted and here's why:
Suppose you have 18v in and 15v out. That is a 3V voltage drop. Current is, for the sake of this example, an arbitrary 300mA. The amount of power dissipated will be 3V x 300mA or 900mW (ALMOST 1 watt). Now, lets say you upped the voltage to 27 volts. You now have 12V x 300mA (the current stays the same regardless of input voltage). So in this case, 12V x 300mA = 3,600mW. OMG, you are now wasting over 3-1/2 watts of power. As 9V batteries are quite expensive and have very low AH ratings, it's fair to say that the more power you throw at it, the more power will be completely wasted. In other words, because current remains the same regardless of input voltage, the greater the voltage drop required for your regulated output, the greater the amount of power dissipated. Also, to be stable, on these type of regulators, the input voltage needs to be higher than the output voltage. I forget how much but it's like 1.2 or 1.5 volts. That is the headroom needed. That means that you are always wasting some amount of power. I realize that you don't want to redo your circuit but for reasons of efficiency, especially when it comes to those LED's, it's best to plan the voltages required by arranging them in a parallel/series array so that a minimum of current dropping resistors are required. Or how about just rigging up 15v with AA or AAA battery holders? The pack will be bigger than the 9V batteries but those batteries are a ton cheaper and will last much much longer AND no regulator required! I'll bet you anything that even if you fed it 12v (8 cells instead of 10), that the LED's will still light and the difference in brightness might not even be noticeable. Saves you 2 more cells, less current consumed, and a smaller pack to boot. Try it, you'll see.
So with respect to your "new" project which requires a 3v regulator...... do you see where I'm going with this?
Thanks CC, You're the modding magician, this project kind of follows all your effortsCpl-Chronic said:
Thanks Scott, I never know if people enjoy reading these lengthy ramblings as I stumble through figuring it out.Old school Scott said:I have learned so much by reading these comprehensive disruptions of your boombox hotroding. Thanks for breaking it down for us.
Cheers OSS
As always, Thanks for chiming in Norm. I am making this up as I go along.Superduper said:
I just read up on the buck converters here. I'll have another look and may consider switching over.
As for why I used two 9v's over ten 1.5v AA or AAA. It was simply about space and weight. I'm not sure how much weight I have added to this radio with the LED's, wiring, clock, switches and extra batteries, but I'm trying to keep it in the "Reasonable" category. Also, since the decks actually work on this radio, I wanted to limit the area I am using in the spare tape deck holder so I can actually put spare tapes in there. Since I removed the light cord control box, the 9v's can go in their place without taking up any more space.
I picked up a package of 9v at CostCo cheap. I forgot the price, but it was cheap. Plus my wife brings home 9v's from work. So I am loaded up on them.
But the real thing is, this radio almost never goes out and when it does, I can swing a few 9v's.
I got the mini heat sinks today. I think I will try them out.
OK, go everything soldered up but the light cord and did an endurance test.
On used energizer industrial 9v's they started to dim after the 2 hour mark. So this will work for what I need it to do.
Next is to solder in the light cord and mount the sensitivity switch.
I am still waiting for the USB plug, then I am done.
On used energizer industrial 9v's they started to dim after the 2 hour mark. So this will work for what I need it to do.
Next is to solder in the light cord and mount the sensitivity switch.
I am still waiting for the USB plug, then I am done.
I have now fitted the light cord circuit board into the side of the radio and (painfully) cut a slice in the side for the sensitivity adjustment wheel to stick through the side. It's now wired up to work off the dual 9v battery setup I have now.
I'll probably put a small piece of black cloth behind the wheel so you can't see into the radio
I'll probably put a small piece of black cloth behind the wheel so you can't see into the radio
Nice work so far Chris,your an inspiration to those of us who are fairly new to tinkering with these cool old boxes. So what song are you gonnba play first when you get it all back together? Just wondering.
Nice work so far Chris,your an inspiration to those of us who are fairly new to tinkering with these cool old boxes. So what song are you gonnba play first when you get it all back together? Just wondering.
That is a good question! What song should I play first?
I just rebelted the decks, haven't tested them, but maybe I should crank up a track from a tape first!
That is a good question! What song should I play first?
I just rebelted the decks, haven't tested them, but maybe I should crank up a track from a tape first!
Nice work Chris. The cut out in the side looks factory!
Nice work!
James....
Thanks Jimmy, I hate cutting into boxes, but sometimes it must be done!
Nice work!
James....
Thanks Jimmy, I hate cutting into boxes, but sometimes it must be done!
Well sir, I'm thinking "Back in the village" by Iron Maiden. You just can't beat the Powerslave album for some kick arse boomin'!
GOOD CALL....Been a long time since I cranked up ye'ol POWERSLAVE! One of Maiden's best!ralrein1 said:
I hate doing stuff like that, But this radio is mine for life. If I do it right and it all works properly, then the next owner should have no trouble cranking it for years to come, after I'm dead of courseSLO said:
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