let's see if i'm getting this right.

When you go to Radio Shack, ask for part number 276-1617. This is a package of 15 general purpose NPN transistors similar to the popular 2N2222 or others called for in most small-signal circuits.

Regards,
AllVol
 
**broken link removed**

i don't know why all my pics come oout fuzzy today but thats the schematic of what i have in the pic. if i switch the collector and emitter around i get pretty much the same results. and as long as theres resistance on the base it works if not nothing happens!!
 
i got part number pn2907-type pnp trans
specs as on box. (max)
VCEO= 40v
vcbo= 60v
vebo=5v
IC=.8A
PD= 625mW
fT= 200mhz

its all they had in stock for pnp's!!
 
hey, buickskill

When you get your transistors from RS (see above for part #) go by the attached schematic.

NOTE: If you are using 32 vdc supply, change the resistor between V+ and the LED to one of about 1500 ohms (brown-green-red striped) and about 15,000 (brown-green-orange) on the base. You would really be better off to pick up Radio Shack part #270-412, a three AAA battery holder ($1.69). This will give you 4.5 volts, enough for most experimental projects.
 

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okey dokey. i will check and see when they have those transistors in because the only one they had was cat number 276-2023. so i got it. i'm gonna up and mess with that a little.
 
Okay, buickskill

That transistor is alright, but you will, as everyone has said, need to reverse the polarity for my diagram.... put V+ (positive) to the emitter, and the collector and base to negative. I still think you need around 5 to 9 volts, however, if no other reason than to understand and comply with most of the circuits floating around.
 
You can use the PNP transistor, ie. the TIP42C with a positive supply.

I'll post a circuit later.
 

The 1k in the base is an over kill.

For Red LED I estimate the collector current will be about 13.6 mA. So you need about 1.36 mA of base current.

Thus for a 5V supply, a 3k3 resistor would suffice.
 
It is hard to read the circuit as it is out of focus. Does your camera have macro function?

As far as I can see, the transistor appears to be a TIP42C. If so, then you're using it the wrong way around.

I'll post a circuit shortly.
 
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Here it is with a 12V supply for a Red LED.
 

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Hi Len

I used 5 volts for supply in my schematic to your 12, thus the difference. I also adjusted for his 32 volts, or at least I think that's what he shows in his fuzzy picture.

Regards,
AllVol
 
I think RadioShack gets "seconds" that don't work. Noobies connect them upside down and backwards and think their circuit is wrong.
 
AllVol said:
Hi Len

I used 5 volts for supply in my schematic to your 12, thus the difference. I also adjusted for his 32 volts, or at least I think that's what he shows in his fuzzy picture.

Regards,
AllVol
Click to expand...
G'day AllVol,
I could not make much out of the picture, so I drew my own.

I used 12 V as he wants to eventually run it on 12.

cheers,
 
mybuickskill6979 said:
i just got back NPN 2n3904 trans they didn't have the one mentioned earlier so i got this one!!
Click to expand...
That transistor should be adequate for your experimenting.

But it has a maximum collector current of 200 mA and a max power dissipation of 625 mW.

So if you are only using it as a saturated switch, then it will be safe up to 200 mA.
 
audioguru said:
I think RadioShack gets "seconds" that don't work. Noobies connect them upside down and backwards and think their circuit is wrong.
Click to expand...
Yes, and I suspect that some don't bother to come back and ask for more help, ie. as you said, assume the circuit is wrong.
 
audioguru said:
I think RadioShack gets "seconds" that don't work.
Click to expand...

Personally, I use Radio Shack components quite often. I have five stores in my area, so usually parts are available when I want them. I can't say I've ever experienced "seconds" or non-working parts, although many transistors will have manufacturer markings. It is important to keep components properly marked and/or separated. Sure, the per component cost seems high, but if one considers the shipping and handling costs, plus usual minimum orders plus the delay in receipt, a few extra cents do not mean much. I do my shopping ahead of time by going to www.radioshack.com , selecting components I want at the best price. I can also make sure which store has the part.

Don't give Radio Shack a bad rep, but they do need to carry more items.

Defensively,
AllVol
 
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