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

[mybuickskill6979]

i have sketch-up cad type drawing stuff. let me see i'll draw it up right now!!

 

[AllVol]

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

 

[mybuickskill6979]

**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!!

 

[mybuickskill6979]

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!!

 

[AllVol]

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.

 

[mybuickskill6979]

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.

 

[AllVol]

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.

 

[mybuickskill6979]

DAMN IT!! i got the wrong type lol!! i got to go back to the RS store!! maybe after while!! i'll go to the store for SODA! hehe!!

 

[ljcox]

You can use the PNP transistor, ie. the TIP42C with a positive supply.

I'll post a circuit later.

 

[ljcox]

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.

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.

 

[ljcox]

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!!

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.

 

[ljcox]

Here it is with a 12V supply for a Red LED.

 

[AllVol]

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

 

[mybuickskill6979]

i just got back NPN 2n3904 trans they didn't have the one mentioned earlier so i got this one!!

 

[audioguru]

I think RadioShack gets "seconds" that don't work. Noobies connect them upside down and backwards and think their circuit is wrong.

 

[ljcox]

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

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,

 

[ljcox]

i just got back NPN 2n3904 trans they didn't have the one mentioned earlier so i got this one!!

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.

 

[ljcox]

I think RadioShack gets "seconds" that don't work. Noobies connect them upside down and backwards and think their circuit is wrong.

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.

 

[AllVol]

I think RadioShack gets "seconds" that don't work.

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

 

[mybuickskill6979]

all vol yes they do and the parts they do carry they need to keep them where you can get to them not in the storage room!!